|
|
|
|
|
| Microbiology, 2002 Feb, 148(Pt 2), 597 - 603 Bacterial deposition in a parallel plate and a stagnation point flow chamber: microbial adhesion mechanisms depend on the mass transport conditions; Bakker DP et al.; Deposition onto glass in a parallel plate (PP) and in a stagnation point (SP) flow chamber of Marinobacter hydrocarbonoclasticus, Psychrobacter sp . and Halomonas pacifica, suspended in artificial seawater, was compared in order to determine the influence of methodology on bacterial adhesion mechanisms . The three strains had different cell surface hydrophobicities, with water contact angles on bacterial lawns ranging from 18 to 85 degrees . Bacterial zeta potentials in artificial seawater were essentially zero . The three strains showed different adhesion kinetics and the hydrophilic bacterium H . pacifica had the greatest affinity for hydrophilic glass . On average, initial deposition rates were two- to threefold higher in the SP than in the PP flow chamber, possibly due to the convective fluid flow toward the substratum surface in the SP flow chamber causing more intimate contact between a substratum and a bacterial cell surface than the gentle collisions in the PP flow chamber . The ratios between the experimental deposition rates and theoretically calculated deposition rates based on mass transport equations not only differed among the strains, but were also different for the two flow chambers, indicating different mechanisms under the two modes of mass transport . The efficiencies of deposition were higher in the SP flow chamber than in the PP flow chamber: 62+/-4 and 114+/-28% respectively . Experiments in the SP flow chamber were more reproducible than those in the PP flow chamber, with standard deviations over triplicate runs of 8% in the SP and 23% in the PP flow chamber . This is probably due to better-controlled convective mass transport in the SP flow chamber, as compared with the diffusion-controlled mass transport in the PP flow chamber . In conclusion, this study shows that bacterial adhesion mechanisms depend on the prevailing mass transport conditions in the experimental set-up used, which makes it essential in the design of experiments that a methodology is chosen with mass transport conditions resembling the problem under investigation. Syst Appl Microbiol, 2001 Nov, 24(3), 342 - 52 Accumulation of osmoprotectants and lipid pattern modulation in response to growth conditions by Halomonas pantelleriense; Romano I et al.; The effects of salinity, growth temperature, pH and composition of the medium on the accumulation of intracellular organic solutes, by nuclear magnetic resonance spectroscopy (NMR) in Halomonas pantelleriense were examined . The modulation of lipid pattern in different growth conditions was also reported . H . pantelleriense accumulated glycine betaine, ectoine, hydroxyectoine and glutamate . The type of osmoprotectant and the relative proportion depended on growth conditions . The main lipids identified by NMR studies were 1,2 diacylglycero-3-phosphorylethanolamine (PEA), 1,2 diacylglycero-3-phosphoryl-glycerol (PG) and cardiolipin, (DPG) . The predominant fatty acids were C16:0 and C18:1, minor fatty acids were C16:1 and C18:0 . The relative percentage of polar lipids and fatty acids were affected by growth conditions. Environ Sci Technol, 2001 Oct 15, 35(20), 4060 - 5 Marine protozoa produce organic matter with a high affinity for PCBs during grazing; Kujawinski EB et al.; Processes influencing organic carbon distribution and composition can control the speciation of organic contaminants such as polychlorinated biphenyls (PCBs) and ultimately determine their residence time in aquatic environments . Protozoan grazers are active in the remineralization and recycling of organic material both in the water column and at the sediment-water interface . Thus, they influence the quality and quantity of potential PCB binding substrates in the suspended and dissolved phases of aqueous systems . In this study, common headspace systems were used to compare the chlorobiphenyl-binding affinity of dissolved organic carbon (DOC) in protozoan and bacterial culture filtrates (<0.2 microm) relative to DOC in a seawater control . Culture filtrates from three marine protozoan species were compared-Uronema sp., Cafeteria sp., and Paraphysomonas imperforata . Each protozoan species was fed the same bacterial prey, Halomonas halodurans, which was also used as a bacterial control . Affinities of culture DOC for {14C}3,3',4,4'-tetrachlorobiphenyl (IUPAC 77) were normalized to DOC and surfactant concentrations . Values of DOC equilibrium partition coefficients (K(DOC)) ranged from 10(4.6) in seawater (Vineyard Sound, MA) to 10(5.4) and 10(5.5) in protist cultures, indicating that grazer-modified DOC was a better sorbent for PCBs than DOC in bacterial or seawater controls. Appl Environ Microbiol, 2001 Sep, 67(9), 3785 - 94 Identification and characterization of bacteria in a selenium-contaminated hypersaline evaporation pond; de Souza MP et al.; Solar evaporation ponds are commonly used to reduce the volume of seleniferous agricultural drainage water in the San Joaquin Valley, Calif . These hypersaline ponds pose an environmental health hazard because they are heavily contaminated with selenium (Se), mainly in the form of selenate . Se in the ponds may be removed by microbial Se volatilization, a bioremediation process whereby toxic, bioavailable selenate is converted to relatively nontoxic dimethylselenide gas . In order to identify microbes that may be used for Se bioremediation, a 16S ribosomal DNA phylogenetic analysis of an aerobic hypersaline pond in the San Joaquin Valley showed that a previously unaffiliated group of uncultured bacteria (belonging to the order Cytophagales) was dominant, followed by a group of cultured gamma-Proteobacteria which was closely related to Halomonas species . Se K-edge X-ray absorption spectroscopy of selenate-treated bacterial isolates showed that they accumulated a mixture of predominantly selenate and a selenomethionine-like species, consistent with the idea that selenate was assimilated via the S assimilation pathway . One of these bacterial isolates (Halomonas-like strain MPD-51) was the best candidate for the bioremediation of hypersaline evaporation ponds contaminated with high Se concentrations because it tolerated 2 M selenate and 32.5% NaCl, grew rapidly in media containing selenate, and accumulated and volatilized Se at high rates (1.65 microg of Se g of protein(-1) x h(-1)), compared to other cultured bacterial isolates. Biochim Biophys Acta, 2001 Jul 2, 1527(1-2), 4 - 10 Calorimetrically obtained information about the efficiency of ectoine synthesis from glucose in Halomonas elongata; Maskow T et al.; Compatible solutes are becoming more and more attractive commercially . Thus, knowledge of the efficiency of synthesis of compatible solutes from different carbon substrates is very important . As the growth rate and rates of formation of compatible solutes correspond to the heat flux, calorimetric measurements are particularly suitable for providing this information . By growing microorganisms continuously in a calorimeter, and generating a feeding stream with gradually increasing salinity without changing any other growth conditions, we were able to determine the efficiency of growth-associated synthesis of compatible solutes . This was shown for Halomonas elongata DMSZ 2581(T) growing on glucose, which synthesizes (at 25 degrees C) 1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid (ectoine) as its main osmotic counterweight . The requirement of biologically usable energy for its growth-associated synthesis was found to be very low: a 100% efficiency of the conversion of the substrate-carbon into ectoine is both theoretically possible and was reached approximately in practice . The growth rate and yield coefficient were essentially independent of the ectoine formation rate, and the rate of substrate-carbon assimilation was far greater than the rate of dissimilation . The specific maximum growth rate was limited by the rate of formation of ectoine. FEBS Lett, 2001 Jan 26, 489(1), 42 - 5 Enzymatic synthesis of a novel trehalose derivative, 3,3'-diketotrehalose, and its potential application as the trehalase enzyme inhibitor; Sode K et al.; We reported the preparation of a novel trehalose derivative based on enzymatic oxidation of trehalose by water-soluble glucose-3-dehydrogenase (G3DH) from marine bacterium Halomonas sp . alpha-15 cells . The product of G3DH enzymatic conversion was 3,3'-diketotrehalose (3,3'dkT), a novel trehalose derivative of which both third hydroxy groups of glucopyranosides were oxidized . 3,3'dkT was revealed to show an inhibitory effect toward pig-kidney and Bombyx mori trehalases . The IC(50) values of 3,3'dkT were 0.8 and 2.5 mM and K(i) values were 0.2 and 0.6 mM for pig-kidney and for B . mori trehalases, respectively . In addition, 3,3'dkT did not show any inhibitory effect on both maltase and mannosidase activities . Therefore, 3,3'dkT was a specific inhibitor of trehalases. Int J Syst Evol Microbiol, 2001 Jan, 51(Pt 1), 51 - 3 Re-examining the 16S rDNA sequence of Halomonas salina; Baumgarte S et al.; Previous reports of 16S rDNA sequencing of members of the family Halomonadaceae Franzmann et al . 1989 include two different sequences that were both attributed to the type strain of Halomonas salina (Valderrama et al . 1991) Dobson and Franzmann 1996 (basonym Deleya salina Valderrama et al . 1991) . The two sequences are sufficiently different for them to belong to two different species within the genus Halomonas . In order to determine which of the two sequences corresponded to that of the type strain of Halomonas salina, the designated type strains of this species were obtained from the ATCC and the DSMZ . It was possible to show that only one of the previous sequences corresponded to the sequences obtained from DSMZ 5928T and ATCC 49509T. Appl Environ Microbiol, 2001 Feb, 67(2), 528 - 38 Microbial thiocyanate utilization under highly alkaline conditions; Sorokin DY et al.; Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS-) at pH 10 were found in highly alkaline soda lake sediments and soda soils . The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources . Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate . The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source . Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs) . The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy . These bacteria could be enriched on mineral medium with thiocyanate at pH 10 . Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher . Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio . The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide . Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis . The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase activity which converted cyanate (CNO-) to ammonia and CO2 . On the other hand, cyanase activity either was absent or was present at very low levels in the autotrophic strains grown on thiocyanate as the sole energy and N source . As a result, large amounts of cyanate were found to accumulate in the media during utilization of thiocyanate at pH 10 in batch and thiocyanate-limited continuous cultures . This is a first direct proof of a "cyanate pathway" in pure cultures of thiocyanate-degrading bacteria . Since it is relatively stable under alkaline conditions, cyanate is likely to play a role as an N buffer that keeps the alkaliphilic bacteria safe from inhibition by free ammonia, which otherwise would reach toxic levels during dissimilatory degradation of thiocyanate. J Appl Microbiol, 2000 Nov, 89(5), 785 - 92 Release of cell-free ice nuclei from Halomonas elongata expressing the ice nucleation gene inaZ of Pseudomonas syringae; Tegos G et al.; Release of ice nuclei in the growth medium of recombinant Halomonas elongata cells expressing the inaZ gene of Pseudomonas syringae was studied in an attempt to produce cell-free active ice nuclei for biotechnological applications . Cell-free ice nuclei were not retained by cellulose acetate filters of 0.2 microm pore size . Highest activity of cell-free ice nuclei was obtained when cells were grown in low salinity (0.5-5% NaCl, w/v) . Freezing temperature threshold, estimated to be below -7 degrees C indicating class C nuclei, was not affected by medium salinity . Their density, as estimated by Percoll density centrifugation, was 1.018 +/- 0.002 gml(-1) and they were found to be free of lipids . Ice nuclei are released in the growth medium of recombinant H . elongata cells probably because of inefficient anchoring of the ice-nucleation protein aggregates in the outer membrane . The ice+ recombinant H . elongata cells could be useful for future use as a source of active cell-free ice nucleation protein. J Microbiol Methods, 2000 Dec 1, 43(1), 45 - 54 Artificial neural network based identification of environmental bacteria by gas-chromatographic and electrophoretic data; Giacomini M et al.; Chemotaxonomic identification techniques are powerful tools for environmental micro-organisms, for which poor diagnostic schemes are available . Whole cellular fatty acid methyl esters (FAME) content is a stable bacterial profile, the analysis method is rapid, cheap, simple to perform and highly automated . Whole-cell protein is an even more powerful tool because it yields information at or below the species level . The description of new species and genera and subsequent continuous rearrangement provide large amounts of data, resulting in large databases . In order to set up suitable software tools to work on such large databases artificial neural network (ANN) based programs have been used to classify and identify marine bacteria at genus and species levels, starting from the fatty acid profiles and protein profiles respectively . We analysed 50 certified strains belonging to Halomonas, Marinomonas, Marinospirillum, Oceanospirillum and Pseudoalteromonas genera . Both supervised and unsupervised ANNs provide a correct classification of the marine strains analyzed . Moreover, a set of 73 marine fresh isolates were used as an example of identification using ANNs . We propose supervised and unsupervised ANNs as a reliable tool for classification of bacteria by means of their FAME and of whole-protein analyses and as a sound basis for a comprehensive artificial intelligence based system for polyphasic taxonomy. FEMS Microbiol Ecol, 2000 Jun 1, 32(3), 249 - 260 High incidence of halotolerant bacteria in Pacific hydrothermal-vent and pelagic environments; Kaye JZ et al.; The abundance of halotolerant microorganisms in hydrothermal-vent and pelagic waters in the North and South Pacific was estimated by the most probable number (MPN) technique using a heterotrophic 16% NaCl medium incubated at 20-24 degrees C . Based on these MPNs and direct counts with epifluorescence microscopy to enumerate the total microbial population, salt-tolerant microbes comprised from <0.01 to >28% of the total microbial community . Fourteen isolates from these MPN enrichments were identified by sequencing a portion of the 16S rRNA gene, and all were found to belong to the genera Halomonas and Marinobacter . The response to salt of mesophilic hydrothermal-vent microbial isolates obtained without selecting for salt tolerance was also examined . Forty-one of 65 strains cultured from hydrothermal plume waters, low-temperature hydrothermal fluids, sulfide rock and an animal specimen at approximately 2000-2200 m depth from the Endeavour Segment of the Juan de Fuca Ridge were subjected to increasing concentrations of NaCl, and over half grew at a NaCl concentration that is lethal to many commonly isolated marine bacteria . At least 36 of the 65 isolates (>/=55%) grew in the enrichment medium supplemented with 10% NaCl; at least 30 of 65 (>/=46%) grew with 16% NaCl; at least 20 of 65 (>/=31%) tolerated 22% NaCl . Based on phylogenetic analysis of the 16S rRNA gene in nine of these 65 isolates, four belonged to the genus Halomonas . These Halomonas strains tolerated 22-27% NaCl . It is possible that a majority of the other 16 isolates which grew with 22% NaCl are also Halomonas based on their degree of halotolerance, morphology, and apparent abundance as revealed by MPN enrichments . The four Halomonas strains obtained without selecting for halotolerance were further characterized physiologically and metabolically . Overall, they grew between -1 degrees C and 40 degrees C, were facultative aerobes, oxidized between 49 and 70 organic compounds according to Biolog plate substrate utilization matrices, grew with oligotrophic quantities of carbon (0.002% yeast extract) in liquid media, reduced nitrate to nitrite, and tolerated up to 0.05-3 mM Cd(2+) . Halomonas is one of the most abundant culturable organisms in the ocean, and its success may be attributed to its metabolic and physiological versatility. Appl Biochem Biotechnol, 2000 Spring, 84-86, 947 - 54 Enzyme electrochemical preparation of a 3-keto derivative of 1,5-anhydro-D-glucitol using glucose-3-dehydrogenase; Sode K et al.; A novel enzymatic organic synthesis was reported, utilizing glucose-3-dehydrogenase (G3DH) and its regeneration via electrochemical methods . We combined the water-soluble G3DH prepared from a marine bacterium, Halomonas sp . alpha-15, and electron mediator with the electrode system in order to regenerate the enzyme . Using this system, the conversion of 1,5-anhydro-D-glucitol (1,5AG), a diabetes marker in human blood, was investigated . The final yield of the product, 3-keto anhydroglucitol (3-ketoAG), which was identified by 13C nuclear magnetic resonance, was 82% based on the initial amount of 1,5AG . The electrochemical yield of the reaction proceeded almost stoichiometrically . The electrochemical conversion rate of 1,5AG was 1.24 mmol/(L.h), and the electrochemical yield of 1,5AG consumption was 80%, whereas that for 3-ketoAG was 60%. Appl Environ Microbiol, 2000 May, 66(5), 1987 - 93 Importance of passive diffusion in the uptake of polychlorinated biphenyls by phagotrophic protozoa; Kujawinski EB et al.; Unicellular protozoan grazers represent a size class of organisms where a transition in the mechanism of chlorobiphenyl (CB) introduction, from diffusion through surface membranes to ingestion of contaminated prey, could occur . This study compares the relative importance of these two processes in the overall uptake of polychlorinated biphenyls by protists . Uptake rates and steady-state concentrations were compared in laboratory cultures of grazing and nongrazing protozoa . These experiments were conducted with a 10-microm marine scuticociliate (Uronema sp.), bacterial prey (Halomonas halodurans), and a suite of 21 CB congeners spanning a range of aqueous solubilities . The dominant pathway of CB uptake by both grazing and nongrazing protozoa was diffusion . Organic-carbon-normalized CB concentrations (in the protozoan cell) were equivalent in grazing and nongrazing protozoa for all congeners studied . Rate constants for uptake into and loss from the protozoan cell were independently determined by using {3,3',4, 4'-(14)C}tetrachlorobiphenyl (IUPAC no . 77), 0.38 +/- 0.03 min(-1) and (1.1 +/- 0.1) x 10(-5) (g of organic carbon)(-1) min(-1), respectively . Magnitudes of the uptake and loss processes were calculated and compared by using a numerical model . The model result was consistent with data from the bioaccumulation experiment and supported the hypothesis that diffusive uptake is faster than ingestive uptake in phagotrophic unicellular protozoa. Int J Syst Evol Microbiol, 2000 Mar, 50 Pt 2, 835 - 46 Phylogenetic analysis of psychrophilic bacteria isolated from the Japan Trench, including a description of the deep-sea species Psychrobacter pacificensis sp . nov; Maruyama A et al.; Phylogenetic positions of psychrophilic bacteria isolated from the Japan Trench were determined by sequencing analysis of PCR-amplified bacterial small subunit (16S) rRNA genes . Between surface and deep-sea psychrophiles, distinct positions clearly differed within the gamma-Proteobacteria . In phylogenetic analysis using neighbour-joining, maximum-parsimony and maximum-likelihood, strains from surface seawater were inferred to be located in the Halomonas aquamarina-meridiana clade within the family Halomonadaceae . Strains from deep seawater (5000-6000 m), however, formed a novel monophyletic clade within the Moraxella-Psychrobacter branch in the family Moraxellaceae, showing separation from terrestrial and Antarctic relatives . These deep-sea strains were also discriminated from other known Psychrobacter species in phenotype, e.g . limited growth in the absence of NaCl (optimum at about 3% NaCl), positive urease activity, acid production from xylose and arabinose, and the presence of multiple fimbriae . DNA relatedness values among six deep-sea strains were > 85% in DNA-DNA hybridization experiments and > 98% in aligned 16S rDNA sequences . From this evidence, a new species, Psychrobacter pacificensis, is proposed for these deep-sea psychrophiles; the type strain of Psychrobacter pacificensis is strain NIBH P2K6T (= IFO 16270T) . Occurrence of psychrobacters in cold Japan Trench deep seawater and at the Antarctic sea surface suggests that deep-sea bacterial habitation and evolution have been mediated by global deep-ocean circulation linked to the sinking of cooled seawater in polar regions. Extremophiles, 2000 Feb, 4(1), 53 - 60 Halomonas magadii sp . nov., a new member of the genus Halomonas, isolated from a soda lake of the East African Rift Valley; Duckworth AW et al.; A number of novel alkaliphilic organotrophic bacteria have been isolated from several saline and alkaline East African soda lakes . The new isolates grow at pH values between 7.0 and 11.0, with pH optima for growth between 9.0 and 10.0 . Growth occurs at total salts concentration between 0% and 20% (w/v) with optimum at 0%-7% (w/v) . Phylogenetic analyses based on 16S rDNA sequence comparison indicate that these isolates are related (>96% similarity) to members of the Halomonadaceae within the gamma-3 subdivision of the Proteobacteria . These analyses indicate that existing species within the Halomonadaceae fell within three main groups, one group comprising the type species of Halomonas, Halomonas elongata, and a number of other known species including one soda lake isolate . A second group constituting most of the remaining known species of Halomonas and related Chromohalobacter spp . includes 3 soda lake isolates with high DNA-DNA homologies . The third group included Halomonas halodenitrificans, Halomonas desiderata, Halomonas cupida, and 13 soda lake isolates . Phenotypic comparisons indicated that the majority of soda lake strains shared similar morphological, phenotypic, and chemotaxonomic properties to known strains of Halomonas but grew under alkaline conditions . The 3 soda lake isolates with high DNA-DNA homologies were, however, significantly different in antibiotic sensitivity pattern and in the utilization of several substrates, were unable to reduce nitrite, and showed low DNA-DNA homologies with known halomonads in the same group . We propose that these isolates comprise a new species of the genus Halomonas that we name Halomonas magadii sp . nov . The type strain is strain 21 MI (NCIMB 13595). Science, 2000 Feb 18, 287(5456), 1245 - 7 Self-assembling amphiphilic siderophores from marine bacteria; Martinez JS et al.; Most aerobic bacteria secrete siderophores to facilitate iron acquisition . Two families of siderophores were isolated from strains belonging to two different genera of marine bacteria . The aquachelins, from Halomonas aquamarina strain DS40M3, and the marinobactins, from Marinobacter sp . strains DS40M6 and DS40M8, each contain a unique peptidic head group that coordinates iron(III) and an appendage of one of a series of fatty acid moieties . These siderophores have low critical micelle concentrations (CMCs) . In the absence of iron, the marinobactins are present as micelles at concentrations exceeding their CMC; upon addition of iron(III), the micelles undergo a spontaneous phase change to form vesicles . These observations suggest that unique iron acquisition mechanisms may have evolved in marine bacteria. J Chromatogr B Biomed Sci Appl, 2000 Jan 14, 737(1-2), 253 - 9 Single-step purification of a recombinant thermostable alpha-amylase after solubilization of the enzyme from insoluble aggregates; Linden A et al.; The expression of the gene encoding a thermostable alpha-amylase (EC 3.2.1.1) (optimal activity at 100 degrees C) from the hyperthermophilic archaeon Pyrococcus woesei in the mesophilic hosts Escherichia coli and Halomonas elongata resulted in the formation of insoluble aggregates . More than 85% of the recombinant enzyme was present within the cells as insoluble but catalytically active aggregates . The recombinant alpha-amylase was purified to homogeneity in a single step by hydrophobic interaction chromatography on a phenyl superose column after solubilization of the enzyme under nondenaturing conditions . The enzyme was purified 258-fold with a final yield of 54%. FEMS Microbiol Lett, 1999 Dec 1, 181(1), 55 - 62 The use of fatty acid methyl ester analysis (FAME) for the identification of heterotrophic bacteria present on three mural paintings showing severe damage by microorganisms; Heyrman J et al.; Mural paintings in Carmona (Spain), Herberstein (Austria) and Greene (Germany), showing visible deterioration by microorganisms, were sampled to investigate the biodiversity of the heterotrophic bacteria present . Four hundred twenty-eight bacterial strains were isolated from which 385 were characterized by fatty acid methyl ester analysis (FAME) . The isolates were grouped into 41 clusters on the basis of their FAME profiles, 20 isolates remained ungrouped . The majority (94%) of the isolates comprised the gram-positive bacteria and the main clusters were identified as Bacillus sp., Paenibacillus sp., Micrococcus sp., Arthrobacter sp . and Staphylococcus sp . Other clusters contain nocardioform actinomycetes and gram-negative bacteria, respectively . A cluster of the latter contained extreme halotolerant bacteria isolated in Herberstein . The FAME profiles of this cluster showed a high similarity with Halomonas. Plasmid, 1999 May, 41(3), 268 - 73 Novel plasmids from alkaliphilic halomonads; Fish SA et al.; Seventeen alkaliphilic halomonads were examined for the presence of plasmids . Of these, eight strains harbored one or more from 5.3 to 33 kb in size, the first plasmids to be identified from an alkaliphilic halomonad source . Restriction and hybridization analysis revealed three strains that maintained an identical 5.9-kb plasmid which we named pAH1, two that had an identical 33-kb plasmid, and three others, of which one carried two plasmids of 5.3 and 15 kb, the former being designated pAH2 . The two final strains maintained plasmids of 15 and 20.5 kb . Restriction mapping of both pAH1 and pAH2 indicated that they have a number of unique restriction sites and are of a small enough size to make them suitable for vector construction . Int J Syst Bacteriol, 1998 Jul, 48 Pt 3, 677 - 86 Carnimonas nigrificans gen . nov., sp . nov., a bacterial causative agent for black spot formation on cured meat products; Garriga M et al.; Nine different strains, CTCBS1T or CTCBS9, were identified to be the causative agents of black spots on the surface of raw cured meat products . The formation of black spots under aerobic conditions is reproducible upon reinoculation of meat products with any of these strains, indicating that they are the causative agent . The strains were Gram-negative, catalase-positive and obligately aerobic rods . The G+C content of DNA of strain CTCBS1T is 56.0 +/- 0.3 mol% . The content of non-polar main fatty acids were 16:0, 16:1, 18:1 and 19:0 cyc . Its phylogenetic position was elucidated by comparative sequence analysis of the 16S rRNA gene . Overall sequence similarity to other bacteria does not exceed 93.3% . Isolate CTCBS1T clustered phylogenetically within the gamma-subclass of the Proteobacteria and is closely related to members of Halomonas (90:5-91.9%) and to Zymobacter palmae (93.3%) . A genetic homogeneity of the nine strains was demonstrated by M13 random amplified polymorphic DNA-PCR, whereas differentiation from other genera, e.g . Zymobacter and Pseudomonas, could easily be achieved by their chemotaxonomic characteristics . Taxonomic data revealed the status of a separate genus for which the name Carnimonas gen . nov., sp., nov . is proposed . Despite chemotaxonomic and physiological similarities, the new genus is at present not a member of the family Halomonadacease because of the lack of two out of 15 descriptive 16S rRNA signature sequences . The first member of the new genus is Carnimonas nigrificans . The use of a specific, 16S rRNA-targeted oligonucleotide primer allowed the identification of all nine strains of C . nigrificans in a PCR assay . Toxicological studies showed no pathogenic potential for C . nigrificans strain CTCBS1T (CECT 4437T). Appl Environ Microbiol, 1997 Aug, 63(8), 3068 - 78 Diversity and association of psychrophilic bacteria in Antarctic sea ice; Bowman JP et al.; The bacterial populations associated with sea ice sampled from Antarctic coastal areas were investigated by use of a phenotypic approach and a phylogenetic approach based on genes encoding 16S rRNA (16S rDNA) . The diversity of bacteria associated with sea ice was also compared with the bacterial diversity of seawater underlying sea ice . Psychrophilic (optimal growth temperature, < or = 15 degrees C; no growth occurring at 20 degrees C) bacterial diversity was found to be significantly enriched in sea ice samples possessing platelet and bottom ice diatom assemblages, with 2 to 9 distinct (average, 5.6 +/- 1.8) psychrophilic taxa isolated per sample . Substantially fewer psychrophilic isolates were recovered from ice cores with a low or negligible population of ice diatoms or from under-ice seawater samples (less than one distinct taxon isolated per sample) . In addition, psychrophilic taxa that were isolated from under-ice seawater samples were in general phylogenetically distinct from psychrophilic taxa isolated from sea ice cores . The taxonomic distributions of psychrotrophic bacterial isolates (optimal growth temperature, > 20 degrees C; growth can occur at approximately 4 degrees C) isolated from sea ice cores and under-ice seawater were quite similar . Overall, bacterial isolates from Antarctic sea ice were found to belong to four phylogenetic groups, the alpha and gamma subdivisions of the Proteobacteria, the gram-positive branch, and the Flexibacter-Bacteroides-Cytophaga phylum . Most of the sea ice strains examined appeared to be novel taxa based on phylogenetic comparisons, with 45% of the strains being psychrophilic . 16S rDNA sequence analysis revealed that psychrophilic strains belonged to the genera Colwellia, Shewanella, Marinobacter, Planococcus, and novel phylogenetic lineages adjacent to Colwellia and Alteromonas and within the Flexibacter-Bacteroides-Cytophaga phylum . Psychrotrophic strains were found to be members of the genera Pseudoalteromonas, Psychrobacter, Halomonas, Pseudomonas, Hyphomonas, Sphingomonas, Arthrobacter, Planococcus, and Halobacillus . From this survey, it is proposed that ice diatom assemblages provide niches conducive to the proliferation of a diverse array of psychrophilic bacterial species. Int J Syst Bacteriol, 1997 Apr, 47(2), 369 - 76 Microbulbifer hydrolyticus gen . nov., sp . nov., and Marinobacterium georgiense gen . nov., sp . nov., two marine bacteria from a lignin-rich pulp mill waste enrichment community; Gonzalez JM et al.; Two numerically important bacteria in marine pulp mill effluent enrichment cultures were isolated . These organisms were gram-negative, rod-shaped, strictly aerobic bacteria . Isolate IRE-31T (T = type strain) produced hydrolytic enzymes for the breakdown of cellulose, xylan, chitin, gelatin, and Tween 80 . It also utilized a variety of monosaccharides, disaccharides, amino acids, and volatile fatty acids for growth . Isolate KW-40T did not utilize natural polymers, but it could grow on a variety of monosaccharides, disaccharides, alcohols, and amino acids . It also utilized methanol and aromatic compounds . The surfaces of both organisms were covered by blebs and vesicles . 16S rRNA analyses placed both organisms in the gamma-3 subclass of the phylum Proteobacteria . They were related to Oceanospirillum linum, Marinomonas vaga, Pseudomonas putida, and Halomonas elongata, although a close association with any of these bacteria was not found . The guanine-plus-cytosine contents of strain IRE-31T and KW-40T were 57.6 and 54.9 mol%, respectively . On the basis of 16S rRNA sequence and phenotypic characterizations, these isolates were different enough so that they could be considered members of new genera . Thus, the following two new genera and species are proposed: Microbulbifer hydrolyticus, with type strain IRE-31 (= ATCC 700072), and Marinobacterium georgiense, with type strain KW-40 (= ATCC 700074). Microbiology, 1996 May, 142 ( Pt 5), 1249 - 54 The role of the outer membrane in formaldehyde tolerance in Escherichia coli VU3695 and Halomonas sp . MAC; Azachi M et al.; To investigate the mechanism of formaldehyde tolerance in Gram-negative bacteria, two formaldehyde-tolerant strains, Escherichia coli VU3695 and Halomonas sp . MAC (DSM 7328), and formaldehyde-sensitive revertants obtained by ethidium bromide or novobiocin treatment were studied . The presence of high levels of formaldehyde dehydrogenase activity alone proved insufficient to confer tolerance to high formaldehyde concentrations, as shown by high activity displayed by formaldehyde-sensitive revertants of Halomonas MAC . Moreover, formaldehyde-tolerant strains also proved to be tolerant to high concentrations of acetaldehyde and glutaraldehyde, which are not oxidized by formaldehyde dehydrogenase . Treatment with sublethal concentrations of EDTA rendered the resistant strains highly sensitive to formaldehyde without affecting the activity of formaldehyde dehydrogenase . Comparison of the outer membrane proteins of formaldehyde-resistant strains with those of their sensitive revertants showed the presence of at least one additional high molecular mass protein in the tolerant strains . It is concluded that formaldehyde tolerance in the bacteria studied depends on the composition and structure of the outer membrane. Can J Microbiol, 1995 Dec, 41(12), 1124 - 31 Description of two new species of Halomonas: Halomonas israelensis sp.nov . and Halomonas canadensis sp.nov; Huval JH et al.; Six well-known strains of halotolerant bacteria, including two strains previously identified only as NRCC 41227 and Ba1, have been compared using 125 phenotypic characters and DNA-DNA hybridization . Although these strains represent some of the most heavily studied salt-tolerant bacteria, they have never been taxonomically compared . The data presented show that these bacteria form a relatively homogeneous group related at the genus level . The taxonomic comparison showed that these six organisms represented four distinct species all related above the 65% Jaccard coefficient level . In addition to two previously identified bacterial species, Halomonas elongata (ATCC 33173T) and Halomonas halodurans (ATCC 29686T), the strains included in this study represent two previously unnamed Halomonas species . These two new taxa have been assigned the names Halomonas israelensis (ATCC 43985T) and Halomonas canadensis (NRCC 41227T = ATCC 43984) . DNA-DNA hybridization show that these two species are related to the type species H . elongata at 54.9 and 48.9%, respectively. Int J Food Microbiol, 1994 May, 22(2-3), 115 - 26 Proteolytic and lipolytic activities of Micrococcus roseus (65), Halomonas elongata (16) and Vibrio sp . (168) isolated from Danish bacon curing brines; Hinrichsen LL et al.; Viable cells, cell free extracts and extracellular concentrates of Micrococcus roseus (65), Halomonas elongata (16) and Vibrio sp . (168) isolated from Danish bacon curing brines were examined for lipase, esterase, proteinase and aminopeptidase activities on natural and synthetic substrates . Micrococcus roseus (65) produced one intracellular esterase with affinity for short chain esters, and two intracellular aminopeptidases with affinity for nonpolar amino acids and L-arginine, respectively . One extracellular aminopeptidase with affinity for L-proline was also observed . Three intracellular esterases with affinity for short chain esters and a membrane bound esterase with affinity for butyric to capric esters were found in Halomonas elongata (16), but almost no aminopeptidase activity was found . Vibrio sp . (168) had four intracellular esterases with affinity for short chain esters and one esterase with affinity for all tested esters . Furthermore, an enzyme, which did not migrate on electrophoretic gels, had activity on all examined esters and tributyrin . Small intracellular activity on L-alanine was observed for this bacterial strain . There was no proteinase activities in the tested bacteria. Int J Syst Bacteriol, 1994 Apr, 44(2), 360 - 1 Reevaluating the classification of Paracoccus halodenitrificans with sequence comparisons of 16S ribosomal DNA; Miller JM et al.; The results of phylogenetic analysis in which 16S ribosomal DNA sequences were compared confirmed previous chemotaxonomic data which suggested that Paracoccus halodenitrificans is inappropriately placed in the genus Paracoccus, which belongs in the alpha subclass of the Proteobacteria . P . halodenitrificans should be placed in the family Halomonadaceae, which belongs in the gamma subclass of the Proteobacteria. Int J Syst Bacteriol, 1993 Oct, 43(4), 665 - 73 Phylogenetic relationships between some members of the genera Deleya, Halomonas, and Halovibrio; Dobson SJ et al.; The genera Halomonas and Deleya, which constitute the family Halomonadaceae, are difficult to differentiate on the basis of phenotypic and chemotaxonomic attributes . DNA-rRNA hybridization studies have indicated that some Halomonas spp . have the same level of relationship to the type species of the genus Deleya as some Deleya spp . A phylogenetic analysis of the 16S rRNA sequences of seven members of the Halomonadaceae indicated that the members of the genera Halomonas and Deleya do not form separate monophyletic subgroups, confirming the lack of any phylogenetic support for retention of these taxa as separate genera . A phylogenetic analysis of the 16S rRNA sequence of Halovibrio variabilis confirmed that this species belongs in the Halomonadaceae . All of the members of the Halomonadaceae examined and Halovibrio variabilis possess a cytosine residue at position 486 (Escherichia coli numbering), which is an extremely rare attribute among the prokaryotes and has been reported in only one other species, Listonella anguillarum . Several other signature characteristics which define this group in the gamma subclass of the Proteobacteria are identified . The Jukes-Cantor distances between members of the family Halomonadaceae, including Halovibrio variabilis, range from 0.086 to 0.000 (the levels of similarity between the 16S rRNA sequences range from 92.6 to 100%) . The members of the genera Halomonas, Deleya, and Halovibrio form a monophyletic group and share common chemotaxonomic and phenotypic characteristics . Subgroups containing members of the genera Halomonas, Deleya, and Halovibrio cannot be resolved on the basis of phylogenetic, chemotaxonomic, or phenotypic data . Our data indicate that the members of the genera Halomonas, Deleya, and Halovibrio should be united in a single genus. Int J Syst Bacteriol, 1992 Oct, 42(4), 568 - 76 Marinobacter hydrocarbonoclasticus gen . nov., sp . nov., a new, extremely halotolerant, hydrocarbon-degrading marine bacterium; Gauthier MJ et al.; On the basis of phenotypical characteristics and analysis of 16S rRNA sequence, a new species belonging to a new genus is described, and the name Marinobacter hydrocarbonoclasticus is proposed . This organism, isolated from Mediterranean seawater near a petroleum refinery, is a gram-negative, aerobic, rod-shaped bacterium . It grows at NaCl concentrations of 0.08 to 3.5 M and uses various hydrocarbons as the sole source of carbon and energy . Its DNA has a guanine-plus-cytosine content of 52.7 mol% . The 16S rRNA analysis shows a clear affiliation between M . hydrocarbonoclasticus and the gamma group of the phylum Proteobacteria . A close phylogenetic relationship appears among the species Marinomonas vaga, Oceanospirillum linum, Halomonas elongata, and Pseudomonas aeruginosa . Because of the impossibility of finding a single most closely related species, we suggest that this bacterium be assigned to a new genus, at least temporarily . The possibility of a revision of this status when new data appear is, however, not excluded . The type strain is M . hydrocarbonoclasticus SP.17 (= ATCC 49840). J Bacteriol, 1988 Jan, 170(1), 132 - 5 Changes in the hydrophobic-hydrophilic cell surface character of Halomonas elongata in response to NaCl; Hart DJ et al.; Phase-partitioning studies of the euryhaline bacterium Halomonas elongata demonstrated that the hydrophobic-hydrophilic nature of the cell surface changed as the bacterium grew in different NaCl concentrations . Mid-log-phase cells grown in a high (3.4 M) NaCl concentration were more hydrophilic than were cells grown in a low (0.05 M) NaCl concentration . Mid-log-phase cells from defined medium containing 3.4 M NaCl normally produced a hydrophobicity reading of only 14 (hexadecane hydrophobicity = 100), while corresponding cells from defined medium containing 0.05M NaCl gave a hydrophobicity reading of 90 . Compared with cells grown in low salt concentrations, cells grown in high salt concentrations were more hydrophilic at all stages of growth . Rapid suspension of log-phase cells grown in 1.37 M NaCl into a 0.05 or 3.4 M NaCl solution produced no detectable rapid changes in surface hydrophobicity . These data suggest that as H . elongata adapts to different NaCl concentrations, it alters the affinity of its outermost cell surface to water. J Bacteriol, 1984 Dec, 160(3), 879 - 83 Cell wall and phospholipid composition and their contribution to the salt tolerance of Halomonas elongata; Vreeland RH et al.; The salt-tolerant bacterium Halomonas elongata makes a variety of physiological adaptations in response to increases in the salt concentration of its growth medium . The cell walls become more compact and internally coherent . The overall lipid pattern shows an increased amount of negatively charged lipids . In addition, the peptidoglycan composition of H . elongata, although not changing in response to increased NaCl, contains the hydrophobic amino acid leucine which is unique among bacterial species . The results suggest that H . elongata is able to live in a wide variety of salt concentrations because it alters its cell physiology in ways which increase both structural integrity and the amount of less-mobile, "structured" cell water, making the cells less susceptible to NaCl-induced dehydration. Can J Microbiol, 1983 Oct, 29(10), 1424 - 9 Effects of NaCl on the uptake of alpha-{14C}aminoisobutyric acid by the halotolerant bacterium Halomonas elongata; Martin EL et al.; The alpha-aminoisobutyric acid (AIB) transport system of the halotolerant bacterium, Halomonas elongata, was examined . Cells were grown in L-alanine defined medium with 0.05, 0.375, 1.37, 2.5, or 3.4 M NaCl . Each group of cells was resuspended in buffered salts with different NaCl concentrations (0.05, 0.375, 1.37, 2.5, and 3.4 M) and the uptake of alpha-{14C}AIB was measured . Optimum AIB uptake occurred in the 0.375 M NaCl solution for the lower salt grown cells and the 1.37 M NaCl solution for the higher salt grown cells . When cells were grown in the higher salt media and suspended in hypoosmotic solutions, appreciable AIB uptake occurred; but for cells grown in lower salt media and suspended in hyperosmotic solutions, the uptake was dramatically reduced . This effect was mainly attributed to cell plasmolysis which in turn resulted in some cell death . The AIB uptake was Na+ specific and this analogue was not metabolized after being transported into the cells . An amino acid competition study gave a pattern similar to that of a marine bacterium.
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
