Appl Biochem Biotechnol, 1998 Spring, 70-72, 311 - 22 Effect of drying on bioremediation bacteria properties; Weekers F et al.; Bioremediation bacteria with drought-resistance characteristics were selected and compared to a collection of 10 strains selected only for their bioremediation properties . Twenty-six strains were selected from dried diesel-polluted soil, and they exhibit a better level of survival during drying, compared to collection bioremediation strains (two orders of magnitude difference) . The lyophilization process does not affect the strains' ability to grow on xenobiotic compound when measured immediately after drying . However, collection bioremediation strains selected only for their bioremediation properties lose up to 80% of their properties when stored at 25 degrees C for 15 d, but the strains selected for their drought resistance lose their properties to a lesser extent during the same period . The maximal growth rate and the rate of xenobiotic degradation of the still-active cells are not affected by the drying process. Folia Microbiol (Praha), 1998, 43(1), 109 - 12 Growth and survival of protozoa isolated from a tannery effluent; Haq RU et al.; Industrial effluent from a tannery was used for the growth of algae in a medium containing various inorganic salts . Growth of algal cells became visible after 7 d . Two species of protozoa were observed to proliferate in the algal culture containing no organic supplement in the medium . The culture was kept bacteria-free by the use of antibiotics and was perpetuated for at least 150 d with no decline in the protozoan population . Efficient growth of protozoa in a culture of algae elucidated new modes of nutrition in protozoa . Cr(VI) was added to the medium to check the resistance of algae and protozoa against this heavy metal . Protozoa showed different degrees of resistance . The results indicate the importance of algae and protozoa in the process of bioremediation. Appl Microbiol Biotechnol, 1998 Apr, 49(4), 482 - 6 Low-temperature bioremediation of a waste water contaminated with anionic surfactants and fuel oil; Margesin R et al.; We conducted a laboratory study at 10 degrees C on the biological decontamination of the waste water from a garage and car-wash that was contaminated with anionic surfactants (57 mg 1(-1)) and fuel oil (184 mg hydrocarbons 1(-1)) . The indigenous microorganisms degraded both contaminants efficiently after biostimulation by an inorganic nutrient supply . After 7 days at 10 degrees C, the residual contaminations were 11 mg anionic surfactants 1(-1) and 26 mg hydrocarbons 1(-1) . After 35 days, only the anionic surfactants had been further reduced to 3 mg 1(-1) . Bioaugmentation of the unfertilized waste water with a cold-adapted inoculum, able to degrade both hydrocarbons (diesel oil) and anionic surfactants (sodium dodecyl sulphate), resulted in a significant increase of the hydrocarbon biodegradation during the first 3 days of decontamination, whereas biodegradation of anionic surfactants was inhibited during the first 21 days following inoculation . Bioaugmentation of the nutrient-amended waste water was without any effect. Can J Microbiol, 1998 Mar, 44(3), 270 - 8 Degradation of hydrocarbons in crude oil by the ascomycete Pseudallescheria boydii (Microascaceae); April TM et al.; Four unique strains of Pseudallescheria boydii were isolated from oil-soaked soils in British Columbia and Alberta and compared to strains from cattle dung and raw sewage . Considerable variability in morphology, colony appearance, colony diameter, and temperature tolerance occurred among the strains . They also varied in the sporogenous states produced in culture; all strains had a Scedosporium anamorph and either the Graphium anamorph or cleistothecial teleomorph . Conspecificity of the six isolates was inferred from their morphology and supported by restriction fragment length polymorphism profiles of the internally transcribed spacer region of rDNA and comparing these to Petriella sordida, a similar taxon in the Microascaceae . Three of the strains isolated from oil-contaminated soil and the strain from sewage were tested for their ability to utilize hydrocarbons by incubation with Prudhoe Bay Crude oil as the sole carbon source . Gas chromatographic analysis of the residual oil revealed that the strains isolated from oil-contaminated soil degraded the linear aliphatics . The strain from sewage, previously shown by others to utilize the volatile n-alkanes (i.e., ethane, propane, and butane), did not utilize the liquid saturate compounds . None of the strains was observed to degrade compounds in the aromatic fraction . Pseudallescheria boydii may be an important agent for in situ bioremediation of saturates in oil-contaminated sites. Antonie Van Leeuwenhoek, 1998 Jan, 73(1), 87 - 94 Enhancement of 2,4-dichlorophenoxyacetic acid (2,4-D) degradation in soil by dissemination of catabolic plasmids; Top EM et al.; Few studies have been done to evaluate the transfer of catabolic plasmids from an introduced donor strain to indigenous microbial populations as a means to remediate contaminated soils . In this work we determined the effect of the conjugative transfer of two 2,4-D degradative plasmids to indigenous soil bacterial populations on the rate of 2,4-D degradation in soil . We also assessed the influence of the presence of 2,4-D on the number of transconjugants formed . The two plasmids used, pEMT1k and pEMT3k, encode 2,4-D degradative genes (tfd) that differ in DNA sequence as well as gene organisation, and confer different growth rates to Ralstonia eutropha JMP228 when grown with 2,4-D as a sole carbon source . In an agricultural soil (Ardoyen) treated with 2,4-D (100 ppm) there were ca . 10(7) CFU of transconjugants per gram bearing pEMT1k as well as a high number of pEMT3k bearing transconjugants (ca 10(6) CFU/g) . In this soil the formation of a high number of 2,4-D degrading transconjugants resulted in faster degradation of 2,4-D as compared to the uninoculated control soil . In contrast, only transconjugants with pEMT1k were detected (at a level of ca . 10(3) CFU/g soil) in the untreated Ardoyen soil . High numbers of transconjugants that carried pEMT1k were also found in a second experiment done using forest soil (Lembeke) treated with 100 ppm 2,4-D . However, unlike in the Ardoyen soil, no transconjugants with pEMT3k were detected and the transfer of plasmid pEMT1k to indigenous bacteria did not result in a higher rate of decrease of 2,4-D . This may be because 2,4-D was readily metabolised by indigenous bacteria in this soil . The results indicate that bioaugmentation with catabolic plasmids may be a viable means to enhance the bioremediation of soils which lack an adequate intrinsic ability to degrade a given xenobiotic. J Chromatogr Sci, 1998 May, 36(5), 253 - 6 Analysis of dissolved methane, ethane, and ethylene in ground water by a standard gas chromatographic technique; Kampbell DH et al.; The measurement of dissolved gases such as methane, ethane, and ethylene in ground water is important in determining whether intrinsic bioremediation is occurring in a fuel- or solvent-contaminated aquifer . A simple procedure is described for the collection and subsequent analysis of ground water samples for these analytes . A helium headspace is generated above a water-filled bottle . Gases that are dissolved in the water partition between the gas and liquid phases and equilibrate rapidly . An aliquot of this headspace is analyzed by gas chromatography to determine the gases concentration in this phase . The concentration of the gas dissolved in the water can then be calculated based on its partitioning properties, as indicated by its Henry's Law constant. Appl Environ Microbiol, 1998 Apr, 64(4), 1447 - 53 Use of 13C nuclear magnetic resonance to assess fossil fuel biodegradation: fate of {1-13C}acenaphthene in creosote polycyclic aromatic compound mixtures degraded by bacteria; Selifonov SA et al.; {1-13C}acenaphthene, a tracer compound with a nuclear magnetic resonance (NMR)-active nucleus at the C-1 position, has been employed in conjunction with a standard broad-band-decoupled 13C-NMR spectroscopy technique to study the biodegradation of acenaphthene by various bacterial cultures degrading aromatic hydrocarbons of creosote . Site-specific labeling at the benzylic position of acenaphthene allows 13C-NMR detection of chemical changes due to initial oxidations catalyzed by bacterial enzymes of aromatic hydrocarbon catabolism . Biodegradation of {1-13C}acenaphthene in the presence of naphthalene or creosote polycyclic aromatic compounds (PACs) was examined with an undefined mixed bacterial culture (established by enrichment on creosote PACs) and with isolates of individual naphthalene- and phenanthrene-degrading strains from this culture . From 13C-NMR spectra of extractable materials obtained in time course biodegradation experiments under optimized conditions, a number of signals were assigned to accumulated products such as 1-acenaphthenol, 1-acenaphthenone, acenaphthene-1,2-diol and naphthalene 1,8-dicarboxylic acid, formed by benzylic oxidation of acenaphthene and subsequent reactions . Limited degradation of acenaphthene could be attributed to its oxidation by naphthalene 1,2-dioxygenase or related dioxygenases, indicative of certain limitations of the undefined mixed culture with respect to acenaphthene catabolism . Coinoculation of the mixed culture with cells of acenaphthene-grown strain Pseudomonas sp . strain A2279 mitigated the accumulation of partial transformation products and resulted in more complete degradation of acenaphthene . This study demonstrates the value of the stable isotope labeling approach and its ability to reveal incomplete mineralization even when as little as 2 to 3% of the substrate is incompletely oxidized, yielding products of partial transformation . The approach outlined may prove useful in assessing bioremediation performance. Appl Environ Microbiol, 1998 Apr, 64(4), 1308 - 12 The Desulfuromonas acetoxidans triheme cytochrome c7 produced in Desulfovibrio desulfuricans retains its metal reductase activity; Aubert C et al.; Multiheme cytochrome c proteins that belong to class III have been recently shown to exhibit a metal reductase activity, which could be of great environmental interest, especially in metal bioremediation . To get a better understanding of these activities, the gene encoding cytochrome c7 from the sulfur-reducing bacterium Desulfuromonas acetoxidans was cloned from genomic DNA by PCR and expressed in Desulfovibrio desulfuricans G201 . The expression system was based on the cyc transcription unit from Desulfovibrio vulgaris Hildenborough and led to the synthesis of holocytochrome c7 when transferred by electrotransformation into the sulfate reducer Desulfovibrio desulfuricans G201 . The produced cytochrome was indistinguishable from the protein purified from Desulfuromonas acetoxidans cells with respect to several biochemical and biophysical criteria and exhibited the same metal reductase activities as determined from electrochemical experiments . This suggests that the molecule was correctly folded in the host organism . Desulfovibrio desulfuricans produces functional multiheme c-type cytochromes from bacteria belonging to a different genus and may be considered a suitable host for the heterologous biogenesis of multiheme c-type cytochromes for either structural or engineering studies . This report, which presents the first example of the transformation of a Desulfovibrio desulfuricans strain by electrotransformation, describes work that is the first necessary step of a protein engineering program that aims to specify the structural features that are responsible for the metal reductase activities of multiheme cytochrome c7. Appl Microbiol Biotechnol, 1998 Jan, 49(1), 117 - 21 Utilization of sorbed compounds by microorganisms specifically isolated for that purpose; Tang WC et al.; A bacterium obtained by enrichment on nonsorbed phenanthrene was unable to degrade phenanthrene sorbed to polyacrylic beads and had little activity on phenanthrene sorbed to lake-bottom sediment . A bacterium obtained by enrichment on phenanthrene sorbed to polyacrylic beads readily mineralized the compound sorbed to the beads or the sediment . Degradation by the second bacterium of phenanthrene sorbed to beads 38-63 microns or 63-150 microns in diameter was more rapid than the rate of desorption of the hydrocarbon in the absence of the bacterium . Little degradation of sorbed, nonleachable phenanthrene in soil was effected by another isolate obtained by enrichment with the nonsorbed hydrocarbon, but a mixed culture and the bacterium obtained by enrichment on the sorbed compound extensively degraded phenanthrene . Because microorganisms specifically obtained for their capacity to degrade sorbed phenanthrene are more active than species not specialized for use of the bound compound, we suggest that microorganisms enriched on nonsorbed compounds may not be appropriate for evaluation of biodegradation and bioremediation of sorbed compounds. Ann N Y Acad Sci, 1997 Nov 21, 829, 263 - 79 Sequential electron acceptor model for evaluation of in situ bioremediation of petroleum hydrocarbon contaminants in groundwater; Brauner JS et al.; Mathematical development and model application is provided for a multiple substrate, sequential electron acceptor model, accounting for hydrodynamic transport, adsorption, and sequential oxygen/iron(III)-based biodegradation . Equations for iron(III)-based biodegradation of petroleum hydrocarbons are developed based on oxygen-inhibited Monod kinetics . The iron(III)-based biodegradation expressions were combined with earlier work by Widdowson and Aelion, to develop the two-dimensional, multiple substrate, oxygen/iron(III) sequential electron acceptor biodegradation model presented here . In addition to mathematical model development, simulations demonstrating the advantages of sequential electron acceptor and multiple substrate biodegradation models are provided . These simulations show that commonly-used single electron acceptor models may underpredict natural, in situ biodegradation potential at sites where indigenous microorganisms are capable of using multiple electron acceptors . Additional simulations show that, for contaminant plumes composed of constituents which biodegrade at different rates and under varying electron acceptor conditions, a multiple substrate model may allow more accurate prediction of both individual contaminant concentrations and the total amount of biodegraded contaminant . Considering that typical contaminant plumes are composed of multiple constituents with varying biodegradation properties and health risks, multiple substrate sequential electron acceptor models have the potential to provide more accurate tracking of individual constituent migration . The model was applied to a leaking UST site in Laurel Bay, South Carolina . Laboratory and monitoring well data presented in Landmeyer et al . have established that the petroleum hydrocarbon contaminants are present in the groundwater and are undergoing sequential oxygen-iron(III)-based biodegradation . Model simulations proved capable of reproducing the trends observed at the Laurel Bay site in that BTX contaminants were removed by sequential biodegradation, occurring first aerobically and subsequently anaerobically, and that iron(III)-reducing organisms biodegrade contaminants only in the absence of oxygen . The BTX compounds were individually but simultaneously modeled, allowing explicit modeling of specific contaminant biodegradation properties (e.g., toluene and xylene are assumed to degrade sequentially and benzene is assumed to degrade aerobically only) . Although simulations presented here can reproduce trends observed at the Laurel Bay site, inclusion of additional electron acceptors and additional model calibration to data from this and other sites is necessary to improve and verify the model's capability to predict the efficacy of intrinsic biodegradation of petroleum hydrocarbon contaminants in groundwater. Ann N Y Acad Sci, 1997 Nov 21, 829, 160 - 78 Bioremediation using composting or anaerobic treatment for ordnance-contaminated soils; Tuomi E et al.; This paper presents the results of the pilot-scale testing of these technologies conducted from December 1994 through March 1995 at the Bangor Naval Submarine Base (Silverdale, Washington) . Goals of the pilot study were to provide cost and design information for the implementation of the full-scale remediation scheduled for mid-1996 . Both aerobic composting and the Simplot Anaerobic Bioremediation (SABRE) process were evaluated for soils contaminated with 2,4,6-trinitrotoluene and other ordnance compounds . Cleanup goals of 33.3 mg/kg (soil D) and 33.0 mg/kg (soil F) were established for TNT . A goal of 9.1 mg/kg was additionally determined for RDX . For soil F, TNT cleanup goals were achieved within 9 days for composting (637 mg/kg to 3 mg/kg) and 40 days for anaerobic treatment (488 mg/kg to 0.7 mg/kg) . For soil D, TNT goals were not statistically achieved using composting (147 mg/kg to 41 mg/kg) or anaerobic treatment (725 mg/kg to 77 mg/kg) during the treatment period . The nature of contamination in soil D (burn disposal of ordnance) may have influenced the treatment performance of both processes. Ann N Y Acad Sci, 1997 Nov 21, 829, 103 - 17 Biotreatment of PAH-contaminated soils/sediments; Bouwer EJ et al.; The importance of chemical conditions and mass transfer effects to in situ bioremediation of PAHs is presented using a case study . In situ bioremediation is being evaluated as a means for remediating a coal-tar contaminated aquifer at the site of a former manufactured gas plant . Two objectives of this work have been to evaluate the potential for the indigenous bacteria to biodegrade coal tar constituents and to identify factors controlling biodegradation rates . Aquifer sediments collected from a variety of locations across the site contain bacteria capable of aerobically mineralizing some of the principal aromatic compounds in the groundwater plume (benzene, naphthalene, and phenanthrene) . Parallel mineralization assays incubated under aerobic and anaerobic conditions strongly suggest that O2 availability is a primary factor controlling the rate and extent of biodegradation . Data indicate that sorption may have also significantly affected biodegradation rates by limiting the bioavailability of the aromatic compounds . A mass transfer-limited numerical model was developed to explore the effect of sorption and bioavailability on biodegradation rates . In this model biodegradation rates are proportional to aqueous concentration, which is directly reduced by sorption . Both biotransformation and bacterial growth are described as being controlled by the rate of desorptive mass transfer . The influence of sorption on biodegradation is quantified by defining a Bioavailability Factor, Bf . A Thiele Modulus which indicates the ratio of characteristic times for sorption and biodegradation is helpful for determining the extent of mass transfer control during biodegradation of the aromatic compounds . This approach is preferred to equilibrium partitioning models, which may overestimate biodegradation rates by failing to consider the effect of rate-limited desorption on bioavailability. Ann N Y Acad Sci, 1997 Nov 21, 829, 97 - 102 Complete reductive dechlorination of trichloroethene by a groundwater microbial consortium; Bolesch DG et al.; Bioremediation promises to be an important technique in the removal of trichloroethene (TCE) and tetrachloroethene (PCE) from contaminated waste sites and contaminated groundwater systems . However, the use of aerobic degradation to degrade these compounds is not always possible . Thus, anaerobic degradation is a promising alternative that may be used to remediate these sites . Recently, literature reports indicate complete anaerobic dechlorination of TCE and PCE by microorganisms enriched from wastewater treatment plants . We report here the complete dechlorination of TCE to ethene in anaerobic microcosms by microorganisms enriched from a TCE contaminated groundwater aquifer using glucose as an electron donor . Initial TCE degradation activity occurred after 10 days of incubation and TCE was no longer detected after 20 days of incubation . During the incubation period, the reductive dechlorination products associated with TCE degradation were detected . Ultimately, all of the TCE was converted to ethene . The glucose culture was further enriched and demonstrated increased rates of TCE conversion to ethene . Our results show that organisms isolated from a contaminated groundwater site are capable of completely degrading TCE to ethene at appreciable rates, and indicate the potential of using in situ anaerobic bioremediation to clean up TCE contaminated sites. Ann N Y Acad Sci, 1997 Nov 21, 829, 36 - 61 Bioavailability and biodegradation kinetics protocol for organic pollutant compounds to achieve environmentally acceptable endpoints during bioremediation; Tabak HH et al.; This paper is an extension of our previous studies on quantitating biodegradation kinetics in soil slurry and compacted soil systems . Previous studies had mainly used phenol as a test contaminant . Phenol represents hydrophilic compounds which exhibit high water solubility and low soil sorption characteristics . This paper extends the experimental protocol using polycyclic aromatic hydrocarbons (PAHs) as the test contaminants . PAHs are hydrophobic compounds with low water solubility and exhibit significant partitioning in soil organic carbon . Degradation rates of PAHs are much slower, thereby requiring acclimation of indigenous soil microbiota using microcosm reactors . The experimental protocol, elaborated in this paper, results in the measurement of biokinetic parameters which can be used to quantitate both ex situ and in situ bioremediation rates and assess the attainable endpoints . Biodegradation studies were conducted for naphthalene using soil slurry, soil wafer, and soil column reactors . Microcosm reactors were set-up to acclimate soil microbiota, and carbon dioxide evolution was used as a measure of acclimation . It was found that reasonable degree of PAH acclimation was achieved after 250 days of microcosm operation . Abiotic adsorption/desorption studies showed that equilibrium was achieved in about 20 hours and approximately 45% of the initial amount of naphthalene is adsorbed by the time equilibrium is attained . Further, desorption was much slower than adsorption with equilibrium being attained in 40 hours . Biokinetic parameters were derived from the cumulative oxygen uptake data of soil slurry, wafer, and column reactors using detailed mathematical models . The cumulative oxygen uptake in all three reactors were almost the same, since naphthalene primarily degraded in the soil phase and the extent of degradation in the aqueous phase was small. Ann N Y Acad Sci, 1997 Nov 21, 829, 30 - 5 An overview of research on the beneficial effects of vegetation in contaminated soil; Erickson LE; Vegetation can enhance in situ bioremediation processes in many applications . Microbial transformations occur in soil and water external to plant roots . Organic contaminants also enter vegetation and are transformed within plants . Research progress is reviewed with emphasis on recent experimental results and mathematical models of contaminant fate in systems where vegetation is present . Plant evapotranspiration provides a solar driven pump-and-treat system which moves contaminants to the rhizosphere and helps to contain them on site . Significant savings have been reported at several field sites where vegetation has been utilized. Ann N Y Acad Sci, 1997 Nov 21, 829, 16 - 29 Roadblocks to the implementation of biotreatment strategies; Talley JW et al.; The Department of Defense (DoD) has over 21,000 contaminated sites requiring some form of remediation . Contaminants on these sites include explosive compounds (i.e., TNT, RDX, HMX), chlorinated solvents (i.e., PCE, TCE, TCA), polycyclic aromatic hydrocarbons (i.e., benzo-a-pyrene), and polychlorinated biphenyls (i.e., aroclors) . Current technology has centered around incineration, air stripping, and the use of activated carbon . Frequently, this technology is not cost effective nor publicly acceptable . Biotreatment offers a possible alternative . Biotreatment can cost effectively eliminate contaminants and avoid the use of harsh chemicals and physical treatments . However, special care must be employed to ensure that the proper remediation system is designed and engineered to optimize clean-up and minimize costs . Unfortunately, not all bioremediation efforts have been successful . In an attempt to develop bioremediation technology from the flask (bench scale) to the field (full-scale design), many scientists and engineers have failed to understand the phenomena that influence bioremediation . Issues such as additional mass transport mechanisms/limitations, the presence of multiple phases, spatial heterogeneities, and unfavorable factors for bacterial growth represent only a few of the phenomena that can limit or complicate biodegradation . Successful bioremediation requires a complete examination of the phenomena that can be observed as the scientist and engineer progress together from the bench to the field . An excellent way to examine these phenomena is by using the conceptual scales of observation: microscale, mesoscale, and macroscale . The microscale represents the level at which chemical/microbial species and reactions can be characterized independently of any transport phenomena . These activities are those occurring at the microbial cell level and generally are the focus of bench level work . The mesoscale is the level at which transport phenomena and system geometry are first apparent, with the exclusion of advective or mixing processes . This scale represents those activities that occur at the pore channel, soil particle or microbial aggregate level . The macroscale is the scale at which you have the ability to discern advective or mixing phenomena . These activities are generally associated on a site level and are the focus of the design engineer . The critical path as bioremediation technology is developed from flask to field is to observe and understand the phenomena that exert influence at each scale of observation so that its effects can be incorporated into the final remediation design. Arch Environ Contam Toxicol, 1998 Feb, 34(2), 128 - 35 Enhanced Heavy Metal Tolerance in Two Strains of Photosynthetic Euglena gracilis by Preexposure to Mercury or Cadmium Devars S, Hernandez R, Moreno-Sanchez R. The effects of different concentrations of Hg, Cd, and Pb on cell growth, oxygen consumption, and production and contents of chlorophyll a and b of Z and B strains of Euglena gracilis was studied . Cell uptake of Cd and Pb was also determined . A greater cell density reached in the presence of Cd2+ correlated with a lower metal uptake capacity in B-strain cells . Cells of Z strain, preexposed to low concentrations of either Hg2+ (1.5 muM) or Cd2+ (50 muM) for several generations showed improved heavy metal tolerance (greater cell density and viability) together with similar metal uptake capacity . Because Cd2+ preadaptation but not Hg2+ pretreatment induced a significant increase in the content of acid-soluble thiols, the data suggest the existence of different mechanisms of heavy metal detoxification in Euglena . The fact that Z-strain cells showed a greater Cd2+ uptake under all the conditions assayed suggests that Z strain would be more suitable for bioremediation of polluted waters. Appl Microbiol Biotechnol, 1997 Dec, 48(6), 677 - 86 Petroleum hydrocarbon bioremediation: sampling and analytical techniques, in situ treatments and commercial microorganisms currently used; Korda A et al.; The sampling and analytical methods, along with available microorganisms, used for in situ hydrocarbon bioremediation are reviewed . Each treatment method is briefly described and its advantages and limitations pertaining to potential applications are evaluated . Bioremediation provides cost-effective, contaminant- and substrate-specific treatments equally successful in reducing the concentrations of single compounds or mixtures of biodegradable materials . In situ treatments rarely yield undesirable byproducts, but precautions and preliminary baseline tests are always recommended . Sampling methods should adhere to good laboratory and field practices and usually do not require highly trained personnel . Analytical methods vary in sensitivity, cost, duration of sample analysis and personnel training required . Voucher specimens of bacterial strains used in bioremediation exist in various repositories (e.g . ATCC, DSM, etc.) or are commercially available, and are usually covered by patent rights . Each one of these strains may yield spectacular results in vitro for specific target compounds . However, the overall success of such strains in treating a wide range of contaminants in situ remains limited . The reintroduction of indigenous microorganisms isolated from the contaminated site after culturing seems to be a highly effective bioremediation method, especially when microorganism growth is supplemented by oxygen and fertilizers. J Ind Microbiol Biotechnol, 1997 Nov-Dec, 19(5-6), 324 - 33 Fungal metabolism of polycyclic aromatic hydrocarbons: past, present and future applications in bioremediation; Cerniglia CE; This article examines the importance of non-ligninolytic and ligninolytic fungi in the bioremediation of polycyclic aromatic hydrocarbon contaminated wastes . The research from the initial studies in Dave Gibson's laboratory to the present are discussed. Appl Microbiol Biotechnol, 1997 Oct, 48(4), 563 - 9 Comparative biotransformation of pentachlorophenol in soils by solid substrate cultures of Lentinula edodes; Okeke BC et al.; Sterilised and non-sterilised soils contaminated with pentachlorophenol (PCP) were inoculated with solid substrate cultures of Lentinula edodes LE2 ("shiitake" mushroom) to simulate monoculture bioremediation treatments and treatments in which the fungus competes with natural microflora . With monocultures of L . edodes, rates of PCP depletion were rapid for the initial 4 weeks and, although thereafter the rate decreased, 99% biotransformation was obtained in 10 weeks . In mixed culture, PCP biotransformation by L . edodes was markedly slower and only 42% of the PCP was depleted after 10 weeks . Maximal rates of PCP transformation, biomass (ergosterol) accumulation and oxidative enzymes (phenol oxidase and manganese-peroxidase) production were observed after 2 weeks of incubation . In monocultures, phenol oxidase activity was 195.5 U g-1 and Mn-peroxidase 138.4 U g-1 . In mixed cultures, fungal enzyme activities were markedly lower: 70.33 U g-1 for phenol oxidase and 85.0 g-1 for Mn-peroxidase . Analyses of soil metabolites after 10 weeks revealed that monocultures of L . edodes had eliminated both PCP and pentachloroanisole . Pentachloroanisole, however, was detected in soils with the mixed microflora . Both dechlorination and mineralisation of the xenobiotic compound were effected by L . edodes LE2. Appl Environ Microbiol, 1997 Dec, 63(12), 4818 - 25 Temperature determines the pattern of anaerobic microbial dechlorination of Aroclor 1260 primed by 2,3,4,6-tetrachlorobiphenyl in Woods Pond sediment; Wu Q et al.; Reductive dechlorination of the Aroclor 1260 residue in Woods Pond (Lenox, Mass.) sediment samples was investigated for a year at incubation temperatures from 4 to 66 degrees C . Sediment slurries were incubated anaerobically with and without 2,3,4,6-tetrachlorobiphenyl (2346-CB; 350 microM) as a primer for dechlorination of the Aroclor 1260 residue . Dechlorination of the Aroclor residue occurred only in live samples primed with 2346-CB and only at 8 to 34 degrees C and 50 to 60 degrees C . The extent and pattern of polychlorinated biphenyl (PCB) dechlorination were temperature dependent . At 8 to 34 degrees C, the dechlorination resulted in 28 to 65% decreases of the hexathrough nonachlorobiphenyls and corresponding increases in the tri- and tetrachlorobiphenyls . At 12 to 30 degrees C, 30 to 40% of the hexa- through nonachlorobiphenyls were dechlorinated in just 3 months . The optimal temperature for overall chlorine removal was 20 to 27 degrees C . We observed four different microbial dechlorination processes with different but partially overlapping temperature ranges, i.e., Process N (flanked meta dechlorination) at 8 to 30 degrees C, Process P (flanked para dechlorination) at 12 to 34 degrees C, Process LP (unflanked para dechlorination) at 18 to 30 degrees C, and Process T (a very restricted meta dechlorination of specific hepta- and octachlorobiphenyls) at 50 to 60 degrees C . These temperature ranges should aid in the development of strategies for the enrichment and isolation of the microorganisms responsible for each dechlorination process . The incubation temperature determined the relative dominance of the four PCB dechlorination processes and the extent and products of dechlorination . Hence, understanding the effects of temperature on PCB dechlorination at contaminated sites should assist in predicting the environmental fate of PCBs or planning bioremediation strategies at those sites. Appl Environ Microbiol, 1997 Oct, 63(10), 3866 - 71 Trichloroethylene biodegradation by mesophilic and psychrophilic ammonia oxidizers and methanotrophs in groundwater microcosms; Moran BN et al.; This study investigated the efficiency of methane and ammonium for stimulating trichloroethylene (TCE) biodegradation in groundwater microcosms (flasks and batch exchange columns) at a psychrophilic temperature (12 degrees C) typical of shallow aquifers in the northern United States or a mesophilic temperature (24 degrees C) representative of most laboratory experiments . After 140 days, TCE biodegradation rates by ammonia oxidizers and methanotrophs in mesophilic flask microcosms were similar (8 to 10 nmol day-1), but {14C}TCE mineralization (biodegradation to 14CO2) by ammonia oxidizers was significantly greater than that by methanotrophs (63 versus 53%) . Under psychrophilic conditions, {14C}TCE mineralization in flask systems by ammonia oxidizers and methanotrophs was reduced to 12 and 5%, respectively . In mesophilic batch exchange columns, average TCE biodegradation rates for methanotrophs (900 nmol liter-1 day-1) were not significantly different from those of ammonia oxidizers (775 nmol liter-1 day-1) . Psychrophilic TCE biodegradation rates in the columns were similar with both biostimulants and averaged 145 nmol liter-1 day-1 . Methanotroph biostimulation was most adversely affected by low temperatures . At 12 degrees C, the biodegradation efficiencies (TCE degradation normalized to microbial activity) of methanotrophs and ammonia oxidizers decreased by factors of 2.6 and 1.6, respectively, relative to their biodegradation efficiencies at 24 degrees C . Collectively, these experiments demonstrated that in situ bioremediation of TCE is feasible at the psychrophilic temperatures common in surficial aquifers in the northern United States and that for such applications biostimulation of ammonia oxidizers could be more effective than has been previously reported. Biodegradation, 1997, 8(2), 97 - 103 Genetic engineering of bacteria and their potential for Hg2+ bioremediation; Chen S et al.; Ion exchange or biosorptive processes for metal removal generally lack specificity in metal binding and are sensitive to ambient conditions, e.g . pH, ionic strength and the presence of metal chelators . In this study, cells of a genetically engineered Escherichia coli strain, JM109, which expresses metallothionein and a Hg2+ transport system after induction were evaluated for their selectivity for Hg2+ accumulation in the presence of sodium, magnesium, or cadmium ions and their sensitivity to pH or the presence of metal chelators during Hg2+ bioaccumulation . The genetically engineered E . coli cells in suspension accumulated Hg2+ effectively at low concentrations (0-20 microM) over a broad range of pH (3 to 11) . The presence of 400 mM sodium chloride, 200 mM magnesium chloride, or 100 microM cadmium ions did not have a significant effect on the bioaccumulation of 5 microM Hg2+, indicating that this process is not sensitive to high ionic strength and is highly selective against sodium, magnesium, or cadmium ions . Metal chelators usually interfere with ion exchange or biosorptive processes . However, two common metal chelators, EDTA and citrate, had no significant effect on Hg2+ bioaccumulation by the genetically engineered strain . These results suggest that this E . coli strain could be used for selective removal of Hg2+ from waste water or from contaminated solutions which are resistant to common treatments . A second potential application would be to remove Hg2+ from Hg(2+)-contaminated soil, sediment, or particulates by washing them with a Hg2+ chelator and regenerating the chelator by passing the solution through a reactor containing the strain. Chemosphere, 1997 Oct, 35(7), 1613 - 21 Analysis of oil components and hydrocarbon-utilizing microorganisms during laboratory-scale bioremediation of oil-contaminated soil of Kuwait; Cho BH et al.; A huge amount of oil-contaminated soil remains unremediated in the Kuwait desert . The contaminated oil has the potentiality to cause pollution of underground water and to effect the health of people in the neighborhood . We have been studying bioremediation of Kuwait oil-contaminated soil . Chemical analyses of biodegraded compounds and isolation of petroleum hydrocarbon-decomposing microorganisms were carried out . From the chemical analyses, it was revealed that the decomposed compounds were mainly saturated fractions from alumina column chromatography and that the aromatic fractions were not decomposed well . Isolation of bacteria was carried out for eight kinds of hydrocarbons which are components of crude petroleum (n-hexadecane, 2,6,10,14-tetramethylpentadecane, 1,4-diisopropylbenzene, naphthalene, 1-methylnaphthalene, phenanthrene, anthracene, and perylene) . Many of the n-hexadecane- and 2,6,10,14-tetramethylpentadecane-decomposing bacteria were isolated, but aromatic compound-decomposing bacteria were not enriched . It was concluded that the slow decomposition of aromatic compounds was due to the low population of aromatic compound-decomposing bacteria in the Kuwait desert soil. Chemosphere, 1997 Oct, 35(7), 1599 - 611 Laboratory-scale bioremediation of oil-contaminated soil of Kuwait with soil amendment materials; Cho BH et al.; A huge amount of oil-contaminated soil remains unremediated in the Kuwait desert . The contaminated oil has the potentiality to cause pollution of underground water and to effect the health of people in the neighborhood . In this study, laboratory scale bioremediation experiments were carried out . Hyponex (Hyponex, Inc.) and bark manure were added as basic nutrients for microorganisms, and twelve kinds of materials (baked diatomite, microporous glass, coconut charcoal, an oil-decomposing bacterial mixture (Formula X from Oppenheimer, Inc.), and eight kinds of surfactants) were applied to accelerate the biodegradation of oil hydrocarbons . 15% to 33% of the contaminated oil was decomposed during 43 weeks' incubation . Among the materials tested, coconut charcoal enhanced the biodegradation . On the contrary, the addition of an oil-decomposing bacterial mixture impeded the biodegradation . The effects of the other materials were very slight . The toxicity of the biodegraded compounds was estimated by the Ames test and the tea pollen tube growth test . Both of the hydrophobic (dichloromethane extracts) and hydrophilic (methanol extracts) fractions showed a very slight toxicity in the Ames test . In the tea pollen tube growth test, the hydrophobic fraction was not toxic and enhanced the growth of pollen tubes. FEMS Microbiol Rev, 1997 Jul, 20(3-4), 517 - 23 Contaminated environments in the subsurface and bioremediation: organic contaminants; Holliger C et al.; Due to leakages, spills, improper disposal and accidents during transport, organic compounds have become subsurface contaminants that threaten important drinking water resources . One strategy to remediate such polluted subsurface environments is to make use of the degradative capacity of bacteria . It is often sufficient to supply the subsurface with nutrients such as nitrogen and phosphorus, and aerobic treatments are still dominating . However, anaerobic processes have advantages such as low biomass production and good electron acceptor availability, and they are sometimes the only possible solution . This review will focus on three important groups of environmental organic contaminants: hydrocarbons, chlorinated and nitroaromatic compounds . Whereas hydrocarbons are oxidized and completely mineralized under anaerobic conditions in the presence of electron acceptors such as nitrate, iron, sulfate and carbon dioxide, chlorinated and nitroaromatic compounds are reductively transformed . For the aerobic often persistent polychlorinated compounds, reductive dechlorination leads to harmless products or to compounds that are aerobically degradable . The nitroaromatic compounds are first reductively transformed to the corresponding amines and can subsequently be bound to the humic fraction in an aerobic process . Such new findings and developments give hope that in the near future contaminated aquifers can efficiently be remediated, a prerequisite for a sustainable use of the precious-subsurface drinking water resources. FEMS Microbiol Rev, 1997 Jul, 20(3-4), 503 - 16 Microbial solubilization and immobilization of toxic metals: key biogeochemical processes for treatment of contamination; White C et al.; Microorganisms play important roles in the environmental fate of toxic metals with a multiplicity of physico-chemical and biological mechanisms effecting transformations between soluble and insoluble phases . Such mechanisms are important components of natural biogeochemical cycles for metals and metalloids with some processes being of potential application to the treatment of contaminated materials . This paper will concentrate on three selected aspects which illustrate the key importance of microorganisms in effecting changes in metal(loid) solubility, namely toxic metal sulfide precipitation by sulfate-reducing bacteria, heterotrophic leaching by fungi, and microbial transformations of metalloids, which includes reduction and methylation . The basic microbiology of these processes is described as well as their environmental significance and use in bioremediation. FEMS Microbiol Rev, 1997 Jul, 20(3-4), 489 - 502 In situ microcosms in aquifer bioremediation studies; Mandelbaum RT et al.; The extent to which aquifer microbiota can be studied under laboratory or simulated conditions is limited by our inability to authentically duplicate natural conditions in the laboratory . Therefore, extrapolation of laboratory results to real aquifer situations is often criticized, unless validation of the data is performed in situ . Reliable data acquisition is critical for the estimation of chemical and biological reaction rates of biodegradation processes in groundwater and as input data for mathematical models . Typically, in situ geobiochemical studies relied on the injection of groundwater spiked with compounds or bacteria of interest into the aquifer, followed by monitoring the changes over time and space . In situ microcosms provide a more confined study site for measurements of microbial reactions, yet closer to natural conditions than laboratory microcosms . Two basic types of in situ aquifer microcosm have been described in recent years, and both originated from in situ instruments initially designed for geochemical measurements . Gillham et al . {Ground Water 28 (1990) 858-862} constructed an instrument that isolates a portion of an aquifer for in situ biochemical rate measurements . More recently Shati et al . {Environ . Sci . Technol . 30 (1996) 2646-2653} modified a multilayer sampler for studying the activity of inoculated bacteria in a contaminated aquifer Keeping in mind recent advances in environmental microbiology methodologies such as immunofluorescence direct counts, oligonucleotide and PCR probes, fatty acid methyl esther analysis for the detection and characterization of bacterial communities, measurement of mRNA and expression of proteins, it is evident that much new information can now be gained from in situ work . Using in situ microcosms to study bioremediation efficiencies, the fate of introduced microorganisms and general geobiochemical aquifer processes can shed more realistic light on the microbial underworld . The aim of this paper is to emphasize the importance of in situ studies and to describe two different concepts of construction and application of in situ microcosms for studying microbial activity in aquifers . The overall goal is to promote the development and utilization of these valuable and largely unexplored tools. Appl Environ Microbiol, 1997 Sep, 63(9), 3378 - 84 Aerobic biodegradation of biphenyl and polychlorinated biphenyls by Arctic soil microorganisms; Mohn WW et al.; We examined the degradation of biphenyl and the commercial polychlorinated biphenyl (PCB) mixture Aroclor 1221 by indigenous Arctic soil microorganisms to assess both the response of the soil microflora to PCB pollution and the potential of the microflora for bioremediation . In soil slurries, Arctic soil microflora and temperate-soil microflora had similar potentials to mineralize {14C}biphenyl . Mineralization began sooner and was more extensive in slurries of PCB-contaminated Arctic soils than in slurries of uncontaminated Arctic soils . The maximum mineralization rates at 30 and 7 degrees C were typically 1.2 to 1.4 and 0.52 to 1.0 mg of biphenyl g of dry soil-1 day-1, respectively . Slurries of PCB-contaminated Arctic soils degraded Aroclor 1221 more extensively at 30 degrees C (71 to 76% removal) than at 7 degrees C (14 to 40% removal) . We isolated from Arctic soils organisms that were capable of psychrotolerant (growing at 7 to 30 degrees C) or psychrophilic (growing at 7 to 15 degrees C) growth on biphenyl . Two psychrotolerant isolates extensively degraded Aroclor 1221 at 7 degrees C (54 to 60% removal) . The soil microflora and psychrotolerant isolates degraded all mono-, most di-, and some trichlorobiphenyl congeners . The results suggest that PCB pollution selected for biphenyl-mineralizing microorganisms in Arctic soils . While low temperatures severely limited Aroclor 1221 removal in slurries of Arctic soils, results with pure cultures suggest that more effective PCB biodegradation is possible under appropriate conditions. Biodegradation, 1997, 8(1), 1 - 13 The effect of inorganic and organic supplements on the microbial degradation of phenanthrene and pyrene in soils; Carmichael LM et al.; The effects of several bioremediation stimulants, including potential metabolism pathway inducers, inorganic/organic nutrients, and surfactants on the metabolism of phenanthrene and pyrene, as well as the population dynamics of PAH degrading microorganisms was examined in five soils with differing background PAH concentrations, exposure histories and physical properties . Most of the supplements either had no significant effect or decreased the mineralization of {14C}-phenanthrene and {14C}-pyrene in soil slurry microcosms . The effect of a particular supplement, however, was often not uniform within or across soils . Decreased mineralization of {14C}-phenanthrene and {14C}-pyrene was usually due to either preferential use of the supplement as carbon source and/or stimulation of non-PAH degrading microorganisms . Many of the supplements increased populations of heterotrophic microorganisms, as measured by plate counts, but did not increase populations of phenanthrene degrading microorganisms, as measured by the {14C}-PAH mineralization MPN analysis or cellular incorporation of {14C}-PAH . These results suggest that the PAH degrading community at each site may be unique in their response to materials added in an attempt to stimulate PAH degradation . The characteristics of the site, including exposure history, soil type, and temporal variation may all influence their response. Curr Opin Biotechnol, 1997 Jun, 8(3), 313 - 6 Bioemulsans: microbial polymeric emulsifiers; Rosenberg E et al.; Bioemulsans are amphipathic proteins and/or polysaccharides that stabilize oil-in-water emulsions . Bioemulsans are produced by a wide diversity of microorganisms and have potential applications in the food, paper, paint, bioremediation, agriculture, detergent and cosmetics industries . The production of the RAG-1 emulsan has been studied in batch-fed fermentors via self-cycling fermentation and with immobilized cells using a Celite support matrix . Bioemulsans have several advantages over lower molecular weight emulsifiers presently used in industry . The last few years have seen a number of new bioemulsans described with commercial applications. Curr Opin Biotechnol, 1997 Jun, 8(3), 285 - 9 Bioremediation of metal contamination; Lovley DR et al.; Recent studies have demonstrated that microbes might be used to remediate metal contamination by removing metals from contaminated water or waste streams, sequestering metals in soils and sediments or solubilizing metals to aid in their extraction . This is primarily accomplished either by biosorption of metals or enzymatically catalyzed changes in the metal redox state . Bioremediation of metals is still primarily a research problem with little large-scale application of this technology. Curr Opin Biotechnol, 1997 Jun, 8(3), 274 - 8 Engineering cytochrome P450s for bioremediation; Kellner DG et al.; Building on the vast knowledge of active site structure and catalytic mechanisms of the P450 monooxygenase systems, significant efforts to utilize the rational design of engineered P450s are emerging as an approach to solve the problems of bioremediation . P450 enzymes are being designed to alter substrate specificities and catalytic efficiency in predefined ways . In addition, random mutagenesis and in vitro evolution are being considered as exciting methods for generating mutant P450s with increased bioremediation abilities. Curr Opin Biotechnol, 1997 Jun, 8(3), 268 - 73 Polycyclic aromatic hydrocarbon bioremediation design; Harayama S; Many polycyclic aromatic hydrocarbons (PAHs) are known to be mutagenic or carcinogenic, and their contamination in soil and aquifer is of great environmental concern . Limited numbers of microorganisms including mycobacteria, Sphingomonas and white rot fungi were found to be capable of degrading PAHs with four or more fused aromatic rings . In white rot fungi, lignin peroxidases are believed to be involved in the degradation of PAHs . In addition to these enzymes, P450 monooxygenases in some fungi were implicated in the degradation of PAHs . The stimulation of PAH biodegradation by the addition of surfactants was observed with some of these microorganisms although the agents were inhibitory on biodegradation with some other microorganisms . Mathematical models were constructed to explain the effect of surfactants on biodegradation . Further studies should be carried out to select the best microorganisms and surfactants for applications to PAH bioremediation. Appl Environ Microbiol, 1997 Jun, 63(6), 2442 - 5 Construction and characterization of Escherichia coli genetically engineered for bioremediation of Hg(2+)-contaminated environments; Chen S et al.; Escherichia coli strains were genetically engineered to express an Hg2+ transport system and metallothionein . Overexpression of a glutathione S-transferase fusion protein of Saccharomyces cerevisiae or pea metallothionein significantly increased the bioaccumulation of Hg2+ transported by MerT and MerP and protected the cells from the accumulated Hg2+ . The recombinant strains have excellent properties for bioremediation of Hg(2+)-contaminated environments. Cytometry, 1997 Mar 1, 27(3), 224 - 32 Quantitative flow cytometric detection of specific microorganisms in soil samples using rRNA targeted fluorescent probes and ethidium bromide; Thomas JC et al.; Specific detection and accurate enumeration of microorganisms in the environment have been hampered by the lack of suitable techniques . A three-parameter flow cytometric method (FCM) was developed to detect quantitatively Sphingomonas sp . strain 107 inoculated into soil samples . By combining light scattering profiles (i.e., morphological properties), ethidium bromide (EtBr) influx (i.e., wall permeability), and fluorescence in situ hybridization against the 16S rRNA (i.e., detection specificity), we could accurately discriminate the bacterium of interest from the indigenous microflora and soil debris . EtBr was used, first, to determine the optimal cell wall permeabilization treatment to allow oligonucleotide probes to enter the bacterial cells and, second, to achieve clear discrimination of fixed cells from debris in soil samples . This method allowed effective qualitative and quantitative analysis by fluorescence in situ hybridization . The results showed that the detection threshold by FCM was 3 x 10(4) cells/g of dry soil . Cell counts deduced from FCM analysis were similar to those obtained by the colony forming unit assay when soils contained fewer than 3 x 106 cells/g dry soil . This method should be useful for either quantitative monitoring of microorganisms inoculated in contaminated soil samples during bioremediation or detecting known bacterial strains in environmental samples. J Ind Microbiol Biotechnol, 1997 Feb-Mar, 18(2-3), 204 - 12 Effects of nutrient dosing on subsurface methanotrophic populations and trichloroethylene degradation; Pfiffner SM et al.; In in situ bioremediation demonstration at the Savannah River Site in Aiken, South Carolina, trichloroethyle degrading microorganisms were stimulated by delivering nutrients to the TCE-contaminated subsurface via horizontal injection wells . Microbial and chemical monitoring of groundwater from 12 vertical wells was used to examine the effects of methane and nutrient (nitrogen and phosphorus) dosing on the methanotrophic populations and on the potential of the subsurface microbial communities to degrade TCE . Densities of methanotrophs increased 3-5 orders of magnitude during the methane- and nutrient-injection phases; this increase coinclded with the higher methane levels observed in the monitoring wells . TCE degradation capacity, although not directly tied to methane concentration, responded to the methane injection, and responded more dramatically to the multiple-nutrient injection . tion . These results support the crucial role of methane, nitrogen, and phosphorus as amended nutrients in TCE bioremediation . The enhancing effects of nutrient dosing on microbial abundance and degradative potentials, coupled with increased chloride concentrations, provided multiple lines of evidence substantiating the effectiveness of this integrated in situ bioremediation process. J Ind Microbiol Biotechnol, 1997 Feb-Mar, 18(2-3), 152 - 60 Utilization of bioremediation processes for the treatment of PAH-contaminated sediments; Hughes JB et al.; The widespread contamination of aquatic sediments by polycyclic aromatic hydrocarbons (PAHs) has created a need for cost-effective remediation processes . Many common PAHs are biodegradable, leading to studies investigating the potential of sediment bioremediation . This article reviews several factors that currently complicate the implementation of sediment bioremediation processes: the effect of complex mixtures of contaminants on the rate and extent of degradation observed, the bioavailability of PAHs in sorbed- and nonaqueous-phase, and methods being evaluated to enhance degradation/availability (surfactant-enhanced solubility, nutrient addition, and bioaugmentation). Arch Environ Contam Toxicol, 1997 Jan, 32(1), 99 - 105 Persistence of polycyclic aromatic hydrocarbon components of creosote under anaerobic enrichment conditions; Sharak Genthner BR et al.; Anaerobic biodegradation of an artificial mixture of polycyclic aromatic hydrocarbons (PAHs), which simulates the PAH component of creosote, was examined under methanogenic, sulfidogenic, and nitrate-reducing conditions using creosote-contaminated sediment as the source of inoculum . PAH degradation, CH4 formation and ion reduction were monitored for up to one year . Despite demonstrating active methanogenic and nitrate-reducing anaerobic bacterial communities, only limited degradation of a few PAHs was observed . Under methanogenic conditions limited degradation of all bicyclic (naphthalene, 1-and 2-methylnaphthalene, biphenyl, and 2,6-dimethylnaphthalene) and one tricyclic PAH, anthraquinone, was detected . 2-Methylanthracene was apparently degraded under nitrate-reducing conditions . Anthraquinone declined in sulfate enrichments, but this decline was not dependent upon sulfate reduction . None of the 4- or 5-ring PAHs were degraded under any of the enrichment conditions . These data indicate that under the anaerobic conditions tested there is only a limited potential to degrade PAHs which must be considered when proposing bioremediation technologies for PAH-contaminated sites, especially if high-molecular-weight PAHs are present. Appl Environ Microbiol, 1996 Dec, 62(12), 4678 - 82 Morphological and metabolic responses to starvation by the dissimilatory metal-reducing bacterium Shewanella alga BrY; Caccavo F Jr et al.; The response of the dissimilatory metal-reducing bacterium Shewanella alga BrY to carbon and nitrogen starvation was examined . Starvation resulted in a gradual decrease in the mean cell volume from 0.48 to 0.2 micron 3 and a dramatic decrease in Fe(III) reductase activity . Growth of starved cultures was initiated with O2, ferric oxyhydroxide, Co(III)-EDTA, or Fe(III)-bearing subsurface materials as the sole electron acceptor . Microbially reduced subsurface materials reduced CrO(4)2- . Starvation of dissimilatory metal-reducing bacteria may provide a means of delivering this metabolism to contaminated subsurface environments for in situ bioremediation. J Biotechnol, 1996 Nov 15, 51(3), 273 - 8 Oil bioremediation using insoluble nitrogen source; Rosenberg E et al.; Oil bioremediation is limited by the availability of nitrogen and phosphorous, which are needed by the bacteria and not present in sufficient amounts in hydrocarbons . The supply of these two essential elements as water-soluble salts presents several problems . These include the rapid dilution of the salts in the large volumes of polluted land or water and their utilization by other bacteria that do not degrade oil . In addition, increasing the concentration of mobile nitrogen creates further environmental problems . The use of hydrophobic sources of nitrogen and phosphorous that have a low water solubility can overcome these problems . We have studied one such compound . F-1, that is not used by most bacteria but serves as a good nitrogen and phosphorous source for those bacterial strains that are capable of utilizing it . We have shown that bacteria using F-1 do not cross-feed other bacterial strains . Moreover, when the concentration of the pollutant is sufficiently reduced, the multiplication of the bacteria slows down until they become a negligible fraction of the bacterial population . Chemical analysis indicated that following a 28-day treatment of Alaskan crude oil, most of the hydrocarbons, including polycyclic aromatics, are degraded to undetectable levels . The C34 and C35 components were also degraded, although their degradation was not completed within this time period . In treatment of a sandy beach that was accidentally polluted with crude heavy oil, about 90% degradation was obtained within about 4 months at an outside average temperature of 5 -10 degrees C. J Magn Reson B, 1996 Oct, 113(1), 9 - 15 Assay for bacteria in porous media by diffusion-weighted NMR; Potter K et al.; In this work, an NMR technique capable of detecting bacterial cells and measuring the cell density in suspension and in porous media has been developed . It is based on the pulsed-field-gradient technique and relies on the fact that extracellular water diffuses freely while intracellular water is completely restricted by the relatively impermeable cell wall of the bacterium . At high wave vectors, the signal from extracellular water is completely suppressed while the signal from intracellular water is comparatively unaffected . This technique has been applied to the mapping of bacterial distributions in porous media . This method is presented as a non-destructive, real-time technique for biomass characterization within laboratory column and flow cell experiments, and possibly for monitoring in situ bioremediation. J Ind Microbiol, 1996 Aug, 17(2), 116 - 23 A comparison of carbon/energy and complex nitrogen sources for bacterial sulphate-reduction: potential applications to bioprecipitation of toxic metals as sulphides; White C et al.; Detailed nutrient requirements were determined to maximise efficacy of a sulphate-reducing bacterial mixed culture for biotechnological removal of sulphate, acidity and toxic metals from waste waters . In batch culture, lactate produced the greatest biomass, while ethanol was more effective in stimulating sulphide production and acetate was less effective . The presence of additional bicarbonate and H2 only marginally stimulated sulphide production . The sulphide output per unit of biomass was greatest using ethanol as substrate . In continuous culture, ethanol and lactate were used directly as efficient substrates for sulphate reduction while acetate yielded only slow growth . Glucose was utilised following fermentation to organic acids and therefore had a deleterious effect on pH . Ethanol was selected as the most efficient substrate due to cost and efficient yield of sulphide . On ethanol, the presence of additional carbon sources had no effect on growth or sulphate reduction in batch culture but the presence of complex nitrogen sources (yeast extract or cornsteep) stimulated both . Cornsteep showed the strongest effect and was also preferred on cost grounds . In continuous culture, cornsteep significantly improved the yield of sulphate reduced per unit of ethanol consumed . These results suggest that the most efficient nutrient regime for bioremediation using sulphate-reducing bacteria required both ethanol as carbon source and cornsteep as a complex nitrogen source. Can J Microbiol, 1996 Aug, 42(8), 791 - 7 Involvement of a surface-active high molecular weight factor in degradation of polycyclic aromatic hydrocarbons by Pseudomonas marginalis; Burd G et al.; A strain of Pseudomonas marginalis PD-14B, isolated from polycyclic aromatic hydrocarbon (PAH) contaminated soil, produced an extracellular surface-active factor of high molecular weight containing protein and lipopolysaccharide . A crude preparation of the factor, obtained from the culture both of cells grown in mineral salts (MS) medium with succinate and yeast extract, affected the extent of PAH degradation by the bacterial cells and prevented flocculation of PAHs in an aqueous suspension . A washed suspension of P . marginalis cells also prevented flocculation of PAH suspensions and emulsified liquid hydrocarbons . Incubation of the factor and the factor-producing strain in the presence of different PAHs resulted in gradual increase of turbidity of the PAH dispersions . The factor markedly stimulated rate and extent of turbidity generation by bacterial cells . The surface-active factor may promote infection of lettuce and other plants by this known pathogen and may also have application in bioremediation. Chemosphere, 1996 Aug, 33(3), 421 - 36 Field examination of ground water quality as an indicator of microbiological activity at gasoline contaminated sites; Norkus RG et al.; Various portable electrodes and an on-line colorimetric test kit were used in the field to examine ground water quality as an indicator of natural bioremediation across two sites in Connecticut having subsurface gasoline contamination . The parameters examined included dissolved oxygen, dissolved carbon dioxide, direct redox potential (Eh), nitrate, ammonia and pH . These parameters permitted delineating regions of aerobic and anaerobic microbiological activity . Variations in these parameters over an eighteen month period along with gas chromatographic analyses of certain gasoline components in the ground water indicated that in-situ bioremediation was effective at containing the petroleum contamination at both sites . It was found that a new on-line colorimetric test kit for the determination of oxygen was more accurate than a commonly used dissolved oxygen electrode. Appl Environ Microbiol, 1996 Jul, 62(7), 2387 - 92 Quantifying the biodegradation of phenanthrene by Pseudomonas stutzeri P16 in the presence of a nonionic surfactant; Grimberg SJ et al.; The low water solubility of polycyclic aromatic hydrocarbons is believed to limit their availability to microorganisms, which is a potential problem for bioremediation of polycyclic aromatic hydrocarbon-contaminated sites . Surfactants have been suggested to enhance the bioavailability of hydrophobic compounds, but both negative and positive effects of surfactants on biodegradation have been reported in the literature . Earlier, we presented mechanistic models of the effects of surfactants on phenanthrene dissolution and on the biodegradation kinetics of phenanthrene solubilized in surfactant micelles . In this study, we combined the biodegradation and dissolution models to quantify the influence of the surfactant Tergitol NP-10 on biodegradation of solid-phase phenanthrene by Pseudomonas stutzeri P16 . Although micellized phenanthrene does not appear to be available directly to the bacterium, the ability of the surfactant to increase the phenanthrene dissolution rate resulted in an overall increase in bacterial growth rate in the presence of the surfactant . Experimental observations could be predicted well by the derived model with measured biokinetic and dissolution parameters . The proposed model therefore can serve as a base case for understanding the physical-chemical effects of surfactants on nonaqueous hydrocarbon bioavailability. Appl Environ Microbiol, 1996 Jul, 62(7), 2381 - 6 Manganese peroxidase mRNA and enzyme activity levels during bioremediation of polycyclic aromatic hydrocarbon-contaminated soil with Phanerochaete chrysosporium; Bogan BW et al.; mRNA extraction from soil and quantitation by competitive reverse transcription-PCR were combined to study the expression of three manganese peroxidase (MnP) genes during removal of polycyclic aromatic hydrocarbons from cultures of Phanerochaete chrysosporium grown in presterilized soil . Periods of high mnp transcript levels and extractable MnP enzyme activity were temporally correlated, although separated by a short (1- to 2-day) lag period . This time frame also coincided with maximal rates of fluorene oxidation and chrysene disappearance in soil cultures, supporting the hypothesis that high ionization potential polycyclic aromatic hydrocarbons are oxidized in soil via MnP-dependent mechanisms . The patterns of transcript abundance over time in soil-grown P . chrysosporium were similar for all three of the mnp mRNAs studied, indicating that transcription of this gene family may be coordinately regulated under these growth conditions. Microbiol Rev, 1996 Jun, 60(2), 342 - 65 Field evaluations of marine oil spill bioremediation; Swannell RP et al.; Bioremediation is defined as the act of adding or improving the availability of materials (e.g., nutrients, microorganisms, or oxygen) to contaminated environments to cause an acceleration of natural biodegradative processes . The results of field experiments and trials following actual spill incidents have been reviewed to evaluate the feasibility of this approach as a treatment for oil contamination in the marine environment . The ubiquity of oil-degrading microorganisms in the marine environment is well established, and research has demonstrated the capability of the indigenous microflora to degrade many components of petroleum shortly after exposure . Studies have identified numerous factors which affect the natural biodegradation rates of oil, such as the origin and concentration of oil, the availability of oil-degrading microorganisms, nutrient concentrations, oxygen levels, climatic conditions, and sediment characteristics . Bioremediation strategies based on the application of fertilizers have been shown to stimulate the biodegradation rates of oil in aerobic intertidal sediments such as sand and cobble . The ratio of oil loading to nitrogen concentration within the interstitial water has been identified to be the principal controlling factor influencing the success of this bioremediation strategy . However, the need for the seeding of natural environments with hydrocarbon-degrading bacteria has not been clearly demonstrated under natural environmental conditions . It is suggested that bioremediation should now take its place among the many techniques available for the treatment of oil spills, although there is still a clear need to set operational limits for its use . On the basis of the available evidence, we have proposed preliminary operational guidelines for bioremediation on shoreline environments. Curr Opin Biotechnol, 1996 Jun, 7(3), 317 - 20 Intrinsic bioremediation: an environmental restoration technology; Hooker BS et al.; In the past year, there has been a dramatic maturation of intrinsic bioremediation technologies . As methods pertinent to the intrinsic bioremediation of fuel hydrocarbons have become better established, a comprehensive protocol has been developed for the validation and prediction of these processes . Study of intrinsic bioremediation of other prevalent contaminants, such as chlorinated aliphatics, polychlorinated biphenyls, and high explosives, has also been undertaken. Curr Opin Biotechnol, 1996 Jun, 7(3), 311 - 6 Bioaugmentation as a soil bioremediation approach; Vogel TM; The debate over the efficacy of bioaugmentation rages on, with research continuing to demonstrate that its advantages for soil bioremediation are difficult to predict; however, when it works, the results are often very encouraging . The difficulties arise from, among others, the diversity of the microorganisms used, environmental heterogeneity, and variations in the influence of critical parameters (e.g . humidity, microbial predation and "bioavailability') which, unfortunately, are not even always identified. Biodegradation, 1996 Jun, 7(3), 239 - 47 Enhanced biodegradation of diesel fuel through the addition of particulate organic carbon and inorganic nutrients in coastal marine waters; Piehler MF et al.; Diesel fuel pollution in coastal waters, resulting from recreational boating and commercial shipping operations, is common and can adversely affect marine biota . The purpose of this study was to examine the effect of additions of particulate organic carbon (POC) in the form of naturally-occurring marsh grass (Spartina alterniflora), inorganic nutrients (nitrogen and phosphorus), inert particles, and dissolved organic carbon (DOC) on diesel fuel biodegradation and to attempt to formulate an effective bioremedial treatment for small diesel fuel spills in marine waters . Various combinations of treatments were added to water samples from a coastal marina to stimulate diesel fuel biodegradation . Diesel fuel was added in concentrations approximating those found in a spill and biodegradation of straight chain aliphatic constituents was estimated by measuring mineralization of 14C hexadecane added to diesel fuel . All treatments that included POC showed stimulation of biodegradation . However, the addition of inert particles (glass fiber filters and nylon screening) caused no stimulation of biodegradation . The addition of nitrogen and phosphorus alone did not result in stimulation of biodegradation, but nitrogen and Spartina (although not phosphorus and Spartina) did result in stimulation above that of Spartina alone . Maximum biodegradation rates were obtained by the addition of the Spartina POC, ammonium, and phosphate . The addition of mannitol, a labile DOC source with POC and phosphate resulted in a decrease in diesel fuel biodegradation as compared to POC and phosphate alone . The seasonal pattern of diesel fuel biodegradation showed a maximum in the summer and a minimum in the winter . Therefore, of the treatments tested, the most effective for bioremediation of diesel fuel in marine waters is the addition of POC, nitrogen, and phosphorus. Rev Argent Microbiol, 1996 Apr-Jun, 28(2), 83 - 98 {Biodegradation of polycyclic aromatic hydrocarbons and its application to the bioremediation of contaminated soils and sludges}; Ferrari MD; Polycyclic aromatic hydrocarbons (PAHs) are a group of priority pollutants due to their toxic, mutagenic, and carcinogenic properties . They are found in high concentration in many soils and sludges, mainly those associated with petroleum, gas-production and wood-preservation industries . Application of microorganisms for the remediation of contaminated soils and sludges has gained interest as a promising technique in comparison to the conventional practices of landfilling, incineration or solvent extraction . This paper reviews the controlling variables of the biodegradation of PAHs as well as the use of solid-phase and slurry-phase bioremediation techniques . The acceptance of bioremediation technology requires the demonstration of its efficacy, reliability, predictability of the field performance from lab-scale treatability studies, and economical advantage . Some limitations in the biodegradation of high-molecular-weight PAHs and failures in the control of scale-depending factors (mass transport, spatial heterogeneities, abiotic losses) can reduce its effectiveness . Methodology used for the systematic evaluation of bioremediation is also reviewed. Can J Microbiol, 1996 Mar, 42(3), 243 - 51 Physicochemical properties of PM-factor, a surface-active agent produced by Pseudomonas marginalis; Burd G et al.; An extracellular surface-active agent, PM-factor, was obtained by high-speed centrifugation from the culture broth of Pseudomonas marginalis PD-14B . PM-factor exhibited emulsifying activity on a broad spectrum of hydrocarbon liquids, including aromatics, aliphatics, crude oil, and creosote . The factor appeared as ball-shaped particles of varying diameter when examined by electron microscopy (0.16-1.4 microns) . Gel filtration chromatography demonstrated a high molecular mass of the factor (> 10(6) Da) . The ultraviolet absorption spectrum manifested a peak in the region 200 nm rather in the region 260-280 nm . Amino acid analysis showed a very low amount of aromatic amino acids residues in the protein moiety of PM-factor . The presence of 3-deoxy-D-mannooctulosonic acid, heptose, hexosamine, phosphorus, and 3-hydroxy fatty acid indicated that PM-factor contained lipopolysaccharide . The emulsifying activity of PM-factor was inhibited strongly by mercuric chloride and moderately by EDTA . Polymyxin B, Ca2+, and Mg2+ markedly stimulated the factors emulsifying activity . Roles of the bioemulsifier in the functioning of P . marginalis as a plant pathogen and in bioremediation are discussed. Biodegradation, 1996-97, 7(6), 463 - 9 Biodegradation of the mixtures of 4-chlorophenol and phenol by Comamonas testosteroni CPW301; Bae HS et al.; A 4-chlorophenol (4-CP)-degrading bacterium, strain CPW301, was isolated from soil and identified as Comamonas testosteroni . This strain dechlorinated and degraded 4-CP via a meta-cleavage pathway . CPW301 could also utilize phenol as a carbon and energy source without the accumulation of any metabolites via the same meta-cleavage pathway . When phenol was added as an additional substrate, CPW301 could degrade 4-CP and phenol simultaneously . The addition of phenol greatly accelerated the degradation of 4-CP due to the increased cell mass . The simultaneous degradation of the 4-CP and phenol is useful not only for enhanced cell growth but also for the bioremediation of both compounds, which are normally present in hazardous waste sites as a mixture. Antonie Van Leeuwenhoek, 1996 Jan, 69(1), 61 - 6 Introduction of a de novo bioremediation activity into anaerobic granular sludge using the dechlorinating bacterium DCB-2; Christiansen N et al.; The strictly anaerobic, pentachlorophenol (PCP) degrading bacterium DCB-2 was immobilized in an Upflow Anaerobic Sludge Blanket (UASB) reactor containing sterile granules . PCP and lactate were fed to the reactor and the concentration of chlorophenols in the effluent were monitored for 641 days . PCP was found to be degraded and transformed into 3,4,5-trichlorophenol in the reactor where DCB-2 introduced PPCP was still transformed to 3,4,5-trichlorophenol when the hydraulic retention time was decreased to six hours which was much lower than the generation time of DCB-2 insuring no free living cells in the reactor . This indicated that DCB-2 was immobilized in the granular layer . A control reactor that contained only sterile granules did not dechlorinate PCP indicating that the performance in the inoculated reactor was only due to the introduced bacteria . Immobilization of DCB-2 in the granules was further demonstrated by adding an antibody raised against DCB-2 to sliced granules . Bacteria thus visualized formed a net structure inside the granules . No DCB-2 bacteria could be found in granules from the control reactor . When lactate was omitted from the influent, the reactor still dechlorinated PCP in accordance with our findings that lactate was not used by DCB-2 . This suggested that the reducing equivalents for reductive dechlorination were derived from the granules themselves . The reactor performance was 120 mumol.l reactor-1.day-1, comparable to the best described performance of a UASB-reactor and to aerobic reactors . Our study demonstrates that granules can be constructed which possess specific abilities such as a dechlorinating activity and at the same time be high performing . This result have implications for eco-engineering of granules for anaerobic treatment of contaminated waters. Appl Biochem Biotechnol, 1996 Spring, 57-58, 971 - 82 Estimating biodegradative gene numbers at a JP-5 contaminated site using PCR; Chandler DP et al.; We have utilized a most-probable-number polymerase chain reaction (MPN-PCR) procedure to estimate gene numbers and biodegradative potential at a jet fuel (JP-5) contaminated site undergoing the first phase of bioremediation . Nucleic acid analysis was used to determine whether a lack of genetic potential for bioremediation was responsible for low levels of oxygen utilization at the site . Total community DNA was extracted and analyzed by PCR for genes (nahAc,alkB, and xylE) known to be involved in the degradation of certain JP-5 constituents . Results indicate that significant aromatic biodegradative potential exists at the site and outlying areas not subjected to engineered remediation, suggesting that physical and/or chemical factors are inhibiting oxygen delivery . xylE and nahAc were often present in significant portions of the microbial community, whereas alkB was rarely detected . This study illustrates the utility of molecular techniques in evaluating biodegradative potential in the field during active bioremediation. Appl Biochem Biotechnol, 1996 Spring, 57-58, 791 - 801 A case study of the natural attenuation of gas condensate hydrocarbons in soil and groundwater; Barker GW et al.; Condensate liquids have been found to contaminate soil and groundwater at two gas production sites in the Denver Basin operated by Amoco Production Co . These sites have been closely monitored since July 1993 to determine whether intrinsic aerobic or anaerobic bioremediation of hydrocarbons occurs at a sufficient rate and to an adequate end point to support a no-intervention decision . Groundwater monitoring and analysis of soil cores suggest that intrinsic bioremediation is occurring at these sites by multiple pathways, including aerobic oxidation, Fe(III) reduction, and sulfate reduction. Science, 1995 Nov 10, 270(5238), 976 - 80 Crystal structure of the biphenyl-cleaving extradiol dioxygenase from a PCB-degrading pseudomonad; Han S et al.; Polychlorinated biphenyls (PCBs) typify a class of stable aromatic pollutants that are targeted by bioremediation strategies . In the aerobic degradation of biphenyl by bacteria, the key step of ring cleavage is catalyzed by an Fe(II)-dependent extradiol dioxygenase . The crystal structure of 2,3-dihydroxybiphenyl 1,2-dioxygenase from a PCB-degrading strain of Pseudomonas cepacia has been determined at 1.9 angstrom resolution . The monomer comprises amino- and carboxyl-terminal domains . Structural homology between and within the domains reveals evolutionary relationships within the extradiol dioxygenase family . The iron atom has five ligands in square pyramidal geometry: one glutamate and two histidine side chains, and two water molecules. Appl Microbiol Biotechnol, 1995 Nov, 43(6), 1128 - 35 Fate of 14C-labeled anthracene and hexadecane in compost-manured soil; Kastner M et al.; Experiments were carried out to evaluate the impact of the addition of ripe compost on the degradation of two 14C-labeled hydrocarbon model compounds (anthracene and hexadecane) in soil . The addition of mature compost (20% dry wt./dry wt) stimulated significantly the disappearance of the extractable fraction of both compounds . With compost, 23% of the labeled anthracene was transformed into 14CO2 and 42% was fixed to the soil matrix irreversibly . In the unsupplemented control reactor, more than 88% of the original anthracene could be recovered by either of two organic extraction procedures . THe formation of non-extractable bound residues was significantly less with 14C-hexadecane since only 21% of the labeled carbon had become non-extractable after 103 days . The results presented show that compost could stimulate the depletion of hydrocarbons by either mineralization or the formation of unextractable bound residues (humification) . The latter process might be a significant route of depletion in soil especially, for those hydrocarbons that are mineralized only slowly . The meaning of this finding for the assessment of soil bioremediation is discussed. Chemosphere, 1995 Nov, 31(9), 4077 - 84 Mass spectral identification of metabolites formed by microbial degradation of polycyclic aromatic hydrocarbons (PAH); Zink G et al.; This paper deals with the identification of PAH metabolites, which are formed during PAH bioremediation . The investigation was performed with trimethylsilylation (TMS) of the sample, following gas chromatographic (GC) separation and mass spectrometry (MS) . The mass spectra were analysed, rules of fragmentation developed and characteristic fragments were presented. Appl Environ Microbiol, 1995 Sep, 61(9), 3323 - 8 Use of starvation promoters to limit growth and selectively enrich expression of trichloroethylene- and phenol-transforming activity in recombinant Escherichia coli {corrected}; Matin A et al.; The expression of much useful bacterial activity is facilitated by rapid growth . This coupling can create problems in bacterial fermentations and in situ bioremediation . In the latter process, for example, it necessitates addition of large amounts of nutrients to contaminated environments, such as aquifers . This approach, termed biostimulation, can be technically difficult . Moreover, the resulting in situ bacterial biomass production can have undesirable consequences . In an attempt to minimize coupling between expression of biodegradative activity and growth, we used Escherichia coli starvation promoters to control toluene monooxygenase synthesis . This enzyme complex can degrade the environmental contaminants trichloroethylene (TCE) and phenol . Totally starving cell suspensions of such strains degraded phenol and TCE . Furthermore, rapid conversions occurred in the postexponential batch or very slow growth (dilution) rate chemostat cultures, and the nutrient demand and biomass formation for transforming a given amount of TCE or phenol were reduced by 60 to 90% . Strong starvation promoters have recently been clones and characterized in environmentally relevant bacteria like Pseudomonas species; thus, starvation promoter-driven degradative systems can now be constructed in such bacteria and tested for in situ efficacy. Appl Environ Microbiol, 1995 Sep, 61(9), 3221 - 6 Phylogenetic comparison of two polycyclic aromatic hydrocarbon-degrading mycobacteria; Govindaswami M et al.; Two mycobacterial strains previously isolated from fossil-fuel-contaminated environments and shown to degrade four- and/or five-ring polycyclic aromatic hydrocarbons were further characterized . The two strains, PYR-I and RJGII-135, had similar growth characteristics, colony morphologies, and scotochromogenic pigmentations . DNA amplification fingerprints obtained with total genomic DNA indicated some strain similarities but with several distinctly different bands . Moreover, phylogenetic analysis based upon essentially full-length 16S rRNA gene sequences separates the two strains as distinct species within the fast-growing group of mycobacteria . Although both strains are thermosensitive, strain PYR-I has the bulged U between positions 184 and 193 characteristic of thermotolerant mycobacteria . Both strains are of potential use for reintroduction into and bioremediation of polycyclic aromatic hydrocarbon-contaminated soils. Appl Biochem Biotechnol, 1995 Jul-Sep, 54(1-3), 291 - 302 Environmental aspects of PAH biodegradation; Shuttleworth KL et al.; Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants, some of which are on the US Environmental Protection Agency priority pollutant list . Consequently, timely clean-up of contaminated sites is important . The lower-mol-wt PAHs are amenable to bioremediation; however, higher-mol-wt PAHs seem to be recalcitrant to microbial degradation . The rates of biodegradation of PAHs are highly variable and are dependent not only on PAH structure, but also on the physicochemical parameters of the site as well as the number and types of microorganisms present . PAHs sorb to organic matter in soils and sediments, and the rate of their desorption strongly influences the rate at which microorganisms can degrade the pollutants . Much of the current PAH research focuses on techniques to enhance the bioavailability and, therefore, the degradation rates of PAHs at polluted sites . Degradation products of PAHs are, however, not necessarily less toxic than the parent compounds . Therefore, toxicity assays need to be incorporated into the procedures used to monitor the effectiveness of PAH bioremediation . In addition, this article highlights areas of PAH research that require further investigation. Appl Biochem Biotechnol, 1995 Jul-Sep, 54(1-3), 277 - 90 Molecular site assessment and process monitoring in bioremediation and natural attenuation . off; Sayler GS et al.; A variety of modern biotechnical approaches are available to assist in optimizing and controlling bioremediation processes . These approaches are broad-ranging, and may include genetic engineering to improve biodegradative performance, maintenance of the environment, and process monitoring and control . In addition to direct genetic engineering strategies, molecular diagnostic and monitoring technology using DNA gene probing methods and new quantitative mRNA analytical procedures allows direct analysis of degradative capacity, activity, and response under in situ conditions . Applications of these molecular approaches in process developments for trichloroethylene (TCE), polychlorinated biphenyls (PCB), and polynuclear aromatic hydrocarbons (PAH) bio-oxidation in soils, aquifer sediments, and ground-water treatment reactors have been demonstrated . Molecular genetic technologies permit not only the development of new processes for bioremediation, but also new process monitoring, control strategies, and molecular optimization paradigms that take full advantage of vast and diverse abilities of microorganisms to destroy problem chemicals. Environ Health Perspect, 1995 Jun, 103 Suppl 5, 63 - 9 Organic halogens in the environment: studies of environmental biodegradability and human exposure; Salkinoja-Salonen M et al.; Organic halogens from chlorobleaching of kraft pulp were not as biorecalcitrant as has been assumed . Fifty percent were removed during biotreatment of wastewater, and 50% of the remaining organohalogens faded in fresh water ecosystems in 200 to 400 days . Molecular size seemed not to hinder biodegradation up to sizes of approximately 2000 daltons . Anoxic biodegradation was of prime importance for halomineralization of pulp bleaching organohalogens but could also lead to toxic metabolites such as vinyl chloride from tri- and tetrachloroethene in anoxic soil . Indigenous soil microbes were unable to clean old organohalogen pollution but had converted chlorophenols into polymeric substances, chlorohumus, which were found bioaccumulable by earthworms in spite of the large (up to 5000 g/mole) molecular sizes . Because of the danger of formation of toxic metabolites, the biochemistry of the xenobiotic degradation must be elucidated before active bioremediation is practiced on polluted soil or water . Groundwater pollution by chlorophenols led to increased disease among the exposed population in one well-studied case . Two further cases of potential environmental health impact are described. Environ Health Perspect, 1995 Jun, 103 Suppl 5, 101 - 5 In situ bioremediation of chlorinated solvents; Semprini L; Chlorinated solvents and their natural transformation products are the most frequently observed groundwater contaminants in the United States . In situ bioremediation using anaerobic or aerobic co-metabolic processes is a promising means of cleaning up contaminated aquifers . Studies show that under natural conditions trichloroethylene can be anaerobically degraded to dichloroethylene, vinyl chloride, and ethylene . Pilot scale field studies of in situ aerobic co-metabolic transformations have shown that indigenous microbes grown on phenol are more effective at degrading trichloroethylene and cis-1,2-dichloroethylene than microbes grown on methane . Modeling studies support field observations and indicate that the removal of trichloroethylene and cis-dichloroethylene results from the biostimulation of an indigenous microbial population . Field tests and modeling studies indicate that, at high TCE concentration, degradation becomes stoichiometrically limited. J Ind Microbiol, 1995 Feb, 14(2), 85 - 93 Bioremediation of organic and metal contaminants with dissimilatory metal reduction; Lovley DR; Dissimilatory metal reduction has the potential to be a helpful mechanism for both intrinsic and engineered bioremediation of contaminated environments . Dissimilatory Fe(III) reduction is an important intrinsic process for removing organic contaminants from aquifers contaminated with petroleum or landfill leachate . Stimulation of microbial Fe(III) reduction can enhance the degradation of organic contaminants in ground water . Dissimilatory reduction of uranium, selenium, chromium, technetium, and possibly other metals, can convert soluble metal species to insoluble forms that can readily be removed from contaminated waters or waste streams . Reduction of mercury can volatilize mercury from waters and soils . Despite its potential, there has as yet been limited applied research into the use of dissimilatory metal reduction as a bioremediation tool. Appl Environ Microbiol, 1995 Jan, 61(1), 8 - 12 Effects of electron donor and acceptor conditions on reductive dehalogenation of tetrachloromethane by Shewanella putrefaciens 200; Picardal F et al.; Shewanella putrefaciens 200 is a nonfermentative bacterium that is capable of dehalogenating tetrachloromethane to chloroform and other, unidentified products under anaerobic conditions . Since S . putrefaciens 200 can respire anaerobically by using a variety of terminal electron acceptors, including NO3-, NO2-, and Fe(III), it provides a unique opportunity to study the competitive effects of different electron acceptors on dehalogenation in a single organism . The results of batch studies showed that dehalogenation of CT by S . putrefaciens 200 was inhibited by O2, 10 mM NO3-, and 3 mM NO2-, but not by 15 mM Fe(III), 15 mM fumarate, or 15 mM trimethylamine oxide . Using measured O2, Fe(III), NO2-, and NO3- reduction rates, we developed a speculative model of electron transport to explain inhibition patterns on the basis of (i) the kinetics of electron transfer at branch points in the electron transport chain, and (ii) possible direct inhibition by nitrogen oxides . In additional experiments in which we used 20 mM lactate, 20 mM glucose, 20 mM glycerol, 20 mM pyruvate, or 20 mM formate as the electron donor, dehalogenation rates were independent of the electron donor used . The results of other experiments suggested that sufficient quantities of endogenous substrates were present to support transformation of tetrachloromethane even in the absence of an exogenous electron donor . Our results should be significant for evaluating (i) the bioremediation potential at sites contaminated with both halogenated organic compounds and nitrogen oxides, and (ii) the bioremediation potential of iron-reducing bacteria at contaminated locations containing significant amounts of iron-bearing minerals. Appl Environ Microbiol, 1995 Jan, 61(1), 234 - 8 Use of filamentous cyanobacteria for biodegradation of organic pollutants; Kuritz T et al.; Biodegradation is increasingly being considered as a less expensive alternative to physical and chemical means of decomposing organic pollutants . Pathways of biodegradation have been characterized for a number of heterotrophic microorganisms, mostly soil isolates, some of which have been used for remediation of water . Because cyanobacteria are photoautotrophic and some can fix atmospheric nitrogen, their use for bioremediation of surface waters would circumvent the need to supply biodegradative heterotrophs with organic nutrients . This paper demonstrates that two filamentous cyanobacteria have a natural ability to degrade a highly chlorinated aliphatic pesticide, lindane (gamma-hexachlorocyclohexane); presents quantitative evidence that this ability can be enhanced by genetic engineering; and provides qualitative evidence that those two strains can be genetically engineered to degrade another chlorinated pollutant, 4-chlorobenzoate. Appl Microbiol Biotechnol, 1994 Dec, 42(4), 499 - 507 Degradation of nitroaromatic compounds by microorganisms; Marvin-Sikkema FD et al.; Nitroaromatic compounds are abundantly present in nature, but are in most cases highly toxic to living organisms . Several microorganisms, however, are capable of mineralizing or converting these compounds . Until now four pathways for the complete degradation of nitroaromatics have been described, which start with either the oxygenolytic or reductive removal of the nitro group from the aromatic ring or with this removal by means of replacement reactions . Besides these conversions many organisms are able to reduce nitroaromatics . The degradation of nitroaromatic compounds does not only occur in pure cultures but also in situ, for example in soil, water and sewage . However, several problems are associated with the application of microorganisms in the bioremediation of contaminated sites, as nitroaromatics or their conversion products may chemically interact with soil particles and cells . Besides the possibilities of applying microorganisms in the cleaning of sites contaminated with nitroaromatics, the use of microorganisms or enzymes in the biocatalytic production of industrially valuable products from nitroaromatics is also discussed. J Ind Microbiol, 1994 Nov, 13(6), 392 - 401 Molecular diagnostics and chemical analysis for assessing biodegradation of polychlorinated biphenyls in contaminated soils; Layton AC et al.; The microbial populations in PCB-contaminated electric power substation capacitor bank soil (TVA soil) and from another PCB-contaminated site (New England soil) were compared to determine their potential to degrade PCB . Known biphenyl operon genes were used as gene probes in colony hybridizations and in dot blots of DNA extracted from the soil to monitor the presence of PCB-degrading organisms in the soils . The microbial populations in the two soils differed in that the population in New England soil was enriched by the addition of 1000 p.p.m . 2-chlorobiphenyl (2-CB) whereas the population in the TVA capacitor bank soil was not affected . PCB degradative activity in the New England soil was indicated by a 50% PCB disappearance (gas chromatography), accumulation of chlorobenzoates (HPLC), and 14CO2 evolution from 14C-2CB . The PCB-degrading bacteria in the New England soil could be identified by their positive hybridization to the bph gene probes, their ability to produce the yellow meta-cleavage product from 2,3-dihydroxybiphenyl (2,3-DHB), and the degradation of specific PCB congeners by individual isolates in resting cell assays . Although the TVA capacitor bank soil lacked effective PCB-degrading populations, addition of a PCB-degrading organism and 10,000 p.p.m . biphenyl resulted in a > 50% reduction of PCB levels . Molecular characterization of soil microbial populations in laboratory scale treatments is expected to be valuable in the design of process monitoring and performance verification approaches for full scale bioremediation. FEMS Microbiol Rev, 1994 Oct, 15(2-3), 307 - 17 Degradation of xenobiotic compounds in situ: capabilities and limits; Bouwer E et al.; Exploiting microorganisms for remediation of waste sites is a promising alternative to groundwater pumping and above ground treatment . The objective of in situ bioremediation is to stimulate the growth of indigenous or introduced microorganisms in regions of subsurface contamination, and thus to provide direct contact between microorganisms and the dissolved and sorbed contaminants for biotransformation . Subsurface microorganisms detected at a former manufactured gas plant site contaminated with coal tars mineralized significant amounts of naphthalene (8-43%) and phenanthrene (3-31%) in sediment-water microcosms incubated for 4 weeks under aerobic conditions . Evidence was obtained for naphthalene mineralization (8-13%) in the absence of oxygen in field samples . These data suggest that biodegradation of these compounds is occurring at the site, and the prospects are good for enhancing this biodegradation . Additional batch studies demonstrated that sorption of naphthalene onto aquifer materials reduced the extent and rate of biodegradation, indicating that desorption rate was controlling the biodegradation performance. Rev Argent Microbiol, 1994 Oct-Dec, 26(4), 157 - 70 {Biodegradability in soil of residual hydrocarbons in petroleum tank bottoms}; Ferrari MD et al.; Biodegradability of hydrocarbons on soils can be applied to the treatment of residues (land treatment) from petroleum refinery as well as the cleaning of contaminated soils (bioremediation) . In this paper we have studied the biodegradability of hydrocarbons from petroleum tank bottom sludges on soil by the autochthonous microbial community . Lab assays were conducted in 1l-beakers under the following conditions: hydrocarbon load 5.3%, total aerobic microorganisms 2.7 x 10(7) CFU/g, hydrocarbon degrading microorganisms (HDM) 2.5 x 10(5) cells/g, incubation temperature 25 degrees C, pH 7.0-7.6, and moisture 10-15% . Soil had the following composition: sand 25%, silt 15%, and clay 20% . Different levels and kind of fertilizers were evaluated . Fertilization increased the rate and the quantity of hydrocarbons degraded . It was degraded about 40% of hydrocarbons in 30-90 days according to the fertilization effected . During biodegradation, the HDM increased 760 times . Assays conducted outdoor on trays showed a similar limit of biodegradation . Changes with time in the fungi population, hydrocarbon class, carbon level, and saturated hydrocarbon profiles were measured too . Data suggests the use of microorganisms having a greater metabolic capacity, specially to degrade those hydrocarbon classes that they have shown to be more resistant to biodegradation (aromatics, resins and asphaltenes). Philos Trans R Soc Lond B Biol Sci, 1994 Jul 29, 345(1311), 81 - 7 The quantification of biodiversity: an esoteric quest or a vital component of sustainable development? Lovejoy TE. Biodiversity relates to sustainable development through a series of direct and indirect uses . These include direct harvest, nature tourism, wild genes improving domestic crops, wild species contributing to crop productivity, pest management, sources of medicine and bioremediation (biologically based environmental clean-up) . Biodiversity relates through services, individual species indicating environmental change or stress, insights into the life sciences and increasingly today, through wealth generated from biodiversity at the level of the molecule . Sustainable development relates to the quantification of biodiversity through organizing information to enable the foregoing activities . It also relates in little-explored ways to ecosystem function, stability and resilience . Biodiversity is already a proven indicator of environmental change in freshwater systems. Nature, 1994 Jul 14, 370(6485), 128 - 31 Stimulated anoxic biodegradation of aromatic hydrocarbons using Fe(III) ligands; Lovley DR et al.; Contamination of ground waters with water-soluble aromatic hydrocarbons, common components of petroleum pollution, often produces anoxic conditions under which microbial degradation of the aromatics is slow . Oxygen is often added to contaminated ground water to stimulate biodegradation, but this can be technically difficult and expensive . Insoluble Fe(III) oxides, which are generally abundant in shallow aquifers, are alternative potential oxidants, but are difficult for microorganisms to access . Here we report that adding organic ligands that bind to Fe(III) dramatically increases its bioavailability, and that in the presence of these ligands, rates of degradation of aromatic hydrocarbons in anoxic aquifer sediments are comparable to those in oxic sediments . We find that even benzene, which is notoriously refractory in the absence of oxygen, can be rapidly degraded . Our results suggest that increasing the bioavailability of Fe(III) by adding suitable ligands provides a potential alternative to oxygen addition for the bioremediation of petroleum-contaminated aquifers. Appl Environ Microbiol, 1994 Jul, 60(7), 2311 - 5 Characterization of metal-binding bioflocculants produced by the cyanobacterial component of mixed microbial mats; Bender J et al.; Mixed-species microbial mats that were dominated by the cyanobacterium Oscillatoria sp . and contained heterotrophic and purple autotrophic bacteria were constructed for specific bioremediation applications . When the mats were challenged with metals, production and secretion of metal-binding extracellular polysaccharide bioflocculants were observed . The concentration of these negatively charged polysaccharides was correlated with the removal of manganese from the water column beneath a surface microbial mat . Bioflocculants from an Oscillatoria sp . that was isolated from the mat were collected and concentrated for characterization . A chromatographic analysis revealed a heterogeneous population of polysaccharides with respect to charge density and molecular size . The subpopulation of polysaccharides which exhibited the highest level of flocculating activity was polyanionic and had a molecular weight of more than 200,000 . A glycosyl analysis of the bioflocculants revealed the presence of galacturonic acid (2.2%) and glucuronic acid (1.86%) . The presence of these components, which were negatively charged at the pH levels generated by the mats during photosynthesis (pH > 7.5), may account for the metal-binding properties of the mats. Appl Biochem Biotechnol, 1994 Jul, 48(1), 11 - 4 Bioremediation of contaminated groundwater; Gunther K et al.; Contaminated groundwater from industrial areas in former East Germany was biologically treated using lab-scale solid-state reactors . The ability of bacterial strains of the autochroneous microflora to utilize representative pollutants was tested. Cent Eur J Public Health, 1994 Jun, 2(1), 27 - 31 Human health and the environment in eastern and central Europe . Report of the conference Prague, Czech Republic, 12-15 April 1993; Bloom A; A group of 46 leading environmental health scientists from 15 nations unanimously agreed to join forces in a new scientific effort to protect human health around the world from the potentially harmful effects of environmental chemicals and radioactive materials . The scientists agreed to establish a non-political European-based, not-for-profit organization whose objectives will be to promote, coordinate and fund environmental health research in order to provide a scientific basis for environmental remediation . The organization will be affiliated with the Conte Institute . The research priorities decided upon for Eastern and Central Europe were as follows: 1 . Research into the effects of toxic metals, such as lead, cadmium, arsenic, and beryllium . 2 . Research in the populations of the region on cancer, birth defects, and other diseases, with emphasis on data sharing across national boundaries, on quality control, and on use of biomarkers of reproductive and other effects . 3 . Studies on the molecular, biochemical, and chromosomal bases for varying genetic susceptibilities to environmentally-induced diseases . 4 . Coordination of research on radiation effects, especially on radiation-exposures resulting from nuclear power and weapons plants . 5 . Research on approaches to bioremediation . 6 . Education and training of professionals and nonprofessionals in environmental health issues, on an international basis . These and other issues will be taken up over time by this new, cooperative scientific research organization, as decided at the Prague Conference. Appl Biochem Biotechnol, 1994 Spring, 45-46, 835 - 45 Bioremediation of petroleum hydrocarbons in soil column lysimeters from Kwajalein island; Phelps TJ et al.; Soil column studies were used to evaluate petroleum hydrocarbon (PHC) remediation in soils from Kwajalein Atoll . Treatments included controls, and combinations of water, air, nutrients, and bioaugmentation with indigenous microbes (W, A, N, and M, respectively) . Microbial colony forming units (CFU) decreased in the control columns and in treatments without air . Treatments including W+A+N and W+A+N+ exhibited increased CFU . One third of the PHC was removed by water and another third was removed by W+A+N and W+A+N+M treatments . Bioaugmentation with indigenous PHC degraders did not enhance bioremediation . Potential for bioremediation was demonstrated by air, water, and nutrient amendments. Rev Environ Contam Toxicol, 1994, 138, 49 - 72 Pollutant degradation by white rot fungi; Barr DP et al.; The white rot fungi technology is very different from other more well-established methods of bioremediation (e.g., bacterial systems) . The differences are primarily due to the mechanisms discussed previously . The unusual mechanisms used by the fungi provide them with several advantages for pollutant degradation, but the complexity of these mechanisms has also made the technology slow to emerge as a viable method of bioremediation . One distinct advantage that white rot fungi have over bacterial systems is that they do not require preconditioning to a particular pollutant . Bacteria must be preexposed to a pollutant to allow the enzymes that degrade the pollutant to be induced . The pollutant must also be present in a significant concentration, otherwise induction of enzyme synthesis will not occur . Therefore, there is a finite level to which pollutants can be degraded by bacteria . In contrast, the degradative enzymes of white rot fungi are induced by nutrient limitation . Thus, cultivate the fungus on a nutrient that is limited in something, and the degradative process will be initiated . Also, because the induction of the lignin-degrading system is not dependent on the chemical, pollutants are degraded to near-nondetectable levels by white rot fungi . Another unique feature of pollutant degradation by white rot fungi involves kinetics . The process of chemical conversion by these fungi occurs via a free-radical process, and thus the degradation of chemicals often follows pseudo-first-order kinetics . In fact, in several studies, it has been found that the rate of mineralization or disappearance of a pollutant is proportional to the concentration of the pollutant . This makes the time required to achieve decontamination more important than the rate of degradation . Because the metabolism of chemicals by bacteria involves mostly enzymatic conversions, pollutant degradation often follows Michaelis-Menton-type kinetics . Therefore, Km values of various degradative enzymes with respect to the pollutant must be considered when using bacteria for bioremediation . Considering this, the solubility of a pollutant or a mixture of pollutants might also present a problem for bacterial degradation . In contrast, using a nonspecific free-radical-based mechanism, the fungi are able to degrade insoluble complex mixtures of pollutants, such as creosote (Aust and Bumpus 1989) and Arochlor (Bumpus and Aust 1987b) . Inexpensive nutrient sources, such as sawdust, wood chips, surplus grains, and agricultural wastes, can be used to effectively cultivate white rot fungi.(ABSTRACT TRUNCATED AT 400 WORDS) Appl Environ Microbiol, 1993 Nov, 59(11), 3686 - 94 In situ growth and activity and modes of penetration of Escherichia coli in unconsolidated porous materials; Sharma PK et al.; Statistically reliable data on the in situ rates of growth, substrate consumption, and product formation are required to test the validity of the mathematical models developed for microbially enhanced oil recovery and in situ bioremediation processes . A simple, replicable porous-core system that could be aseptically divided into sections at various times was developed to follow the kinetics of microbial growth and metabolism in situ . This core system was used to study the kinetics of growth and the mode of penetration of strains of Escherichia coli through anaerobic, nutrient-saturated, fine Ottawa sand (permeability of 7.0 microns2 and porosity of 37%) under static conditions . The in situ rate of growth of a wild-type, motile, chemotactic strain, RW262, was two times slower inside cores than it was in liquid cultures . The mode of metabolism of galactose by strain RW262 was not altered inside cores, as acetate wa