Appl Microbiol Biotechnol . 2005 Jan 13; {Epub ahead of print} Evaluation of procedures to acclimate a microbial fuel cell for electricity production; Kim JR et al.; A microbial fuel cell (MFC) is a relatively new type of fixed film bioreactor for wastewater treatment, and the most effective methods for inoculation are not well understood . Various techniques to enrich electrochemically active bacteria on an electrode were therefore studied using anaerobic sewage sludge in a two-chambered MFC . With a porous carbon paper anode electrode, 8 mW/m(2) of power was generated within 50 h with a Coulombic efficiency (CE) of 40% . When an iron oxide-coated electrode was used, the power and the CE reached 30 mW/m(2) and 80%, respectively . A methanogen inhibitor (2-bromoethanesulfonate) increased the CE to 70% . Bacteria in sludge were enriched by serial transfer using a ferric iron medium, but when this enrichment was used in a MFC the power was lower (2 mW/m(2)) than that obtained with the original inoculum . By applying biofilm scraped from the anode of a working MFC to a new anode electrode, the maximum power was increased to 40 mW/m(2) . When a second anode was introduced into an operating MFC the acclimation time was not reduced and the total power did not increase . These results suggest that these active inoculating techniques could increase the effectiveness of enrichment, and that start up is most successful when the biofilm is harvested from the anode of an existing MFC and applied to the new anode. Curr Opin Infect Dis, 2005 Feb, 18(1), 37 - 41 Prevention of catheter-associated urinary tract infection; Trautner BW et al.; PURPOSE OF REVIEW: The underlying cause of catheter-associated urinary tract infection is biofilm formation by uropathogens on the urinary catheter . Biofilm is a relatively new concept in medicine, and current measures to prevent biofilm formation are inadequate . Considerable work is being done in this area, but little clinical progress has been made . The purpose of this review is to analyze recent publications concerning prevention of catheter-associated urinary tract infection . RECENT FINDINGS: Several recent studies have elucidated aspects of biofilm formation in catheter-associated urinary tract infection . Other researchers are working on methods to disrupt biofilm formation on catheter surfaces . At the same time, the magnitude of the problem of catheter-associated urinary tract infection has increased awareness of the effectiveness of basic infection control measures . A modern approach to infection control may include computerized ordering systems that minimize unnecessary days of catheterization . Finally, consumption of cranberry juice products and bacterial interference are two novel approaches to urinary tract infection prevention . SUMMARY: Biofilm-disrupting strategies offer promise for the future but have little immediate applicability . Implementation of infection control measures to improve catheter function and remove unnecessary catheters can be done at the present time . In general, prevention of catheter-associated urinary tract infection remains an elusive goal . More basic research at the level of pathogenesis is needed so that novel strategies can be designed. New Microbiol, 2004 Oct, 27(4), 391 - 7 Detection of DNA from periodontal pathogenic bacteria in biofilm obtained from waterlines in dental units; Montebugnoli L et al.; Direct person-to-person transmission of periodontal bacteria through saliva has recently been widely reported and dental units have been demonstrated to retract saliva from patients under treatment and to release it into the mouths of subjects undergoing the next operation . In this study the presence of a group of periodontal pathogenic bacteria inside waterlines in dental units was investigated using polymerase chain reaction (PCR) based methods . Briefly, 18 dental units of three different manufacturers were studied . Dental units were divided into two groups according to their prevalent use in routine practice . The first group consisted of nine dental units characterized by the frequent use of high-speed dental hand-pieces directly inside the mouth and in contact with patients' saliva . The second group, as a control, consisted of nine dental units where high-speed dental hand-pieces were not in use . A one cm section of the waterline tubing connected to the high-speed hand-piece was removed from each dental unit to evaluate the presence of DNA of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Treponema denticola . Two specimens were positive for Prevotella intermedia DNA . All the positive results were from samples obtained from dental units categorised in the first group . These findings clearly suggest that dental units have the potential to transmit periodontal pathogens . Manufacturers should be invited to design dental units that incorporate automated devices to disinfect DUWLs between patients with minimal effort by dental staff. New Microbiol, 2004 Oct, 27(4), 361 - 7 Enhanced biofilm-production in pathogens isolated from patients with rare metabolic disorders; Debbia EA et al.; Biofilm-producing bacteria were isolated from the urine of 19 patients with very rare metabolic disorders including: hyperlactacidaemia (8 cases), sugar intolerance and gammopathy (1 case), cystinuria (2 cases), Parkinson's disease (1 case), lipidaemia (2 cases), hyperaminoaciduria (1 case) and others (4 cases) . A total of 34 strains were collected, Gram-negative and gram-positive microorganisms were equally distributed among the slime-producing bacteria, with a prevalence of Staphylococcus epidermidis (30%) the most frequent microorganism isolated together with Escherichia coli and Proteus mirabilis that accounted for 15% of this group of strains . A quantitative assay of the biofilm production revealed that in Gram-positive pathogens it was three times greater than that observed in bacteria collected from patients not affected by metabolic diseases (p = 0.0001) . In Gram-negative strains the biofilm synthesis was 2.2 times higher than those detected in the same bacteria isolated in the absence of metabolic disorders (p = 0.0033) . The results observed indicate that biofilm production is enhanced in bacteria isolated from the urine of patients with metabolic disorders . It is suggested that unusual metabolites might facilitate pathogen production of biofilm found in the urine of these patients. Compend Contin Educ Dent, 2004 Jul, 25(7 Suppl 1), 16 - 25 Periodontal inflammation: from gingivitis to systemic disease? Scannapieco FA. There has been a resurgence of interest in recent years in the systemic effects of oral infections such as periodontal diseases . The study of the various means by which periodontal infections and inflammation may influence a variety of systemic conditions is collectively referred to as periodontal medicine . The periodontium responds to tooth-borne biofilm (dental plaque) by the process of inflammation . Dental biofilms release a variety of biologically active products, such as bacterial lipopolysaccharides (endotoxins), chemotactic peptides, protein toxins, and organic acids . These molecules stimulate the host to produce a variety of responses, among them the production and release of potent agents known as cytokines . These include interleukin-1 beta, interleukin-8, prostaglandins, and tumor necrosis factor-alpha . There is a spectrum of periodontal response to these molecules, from mild gingivitis to severe destructive periodontitis . These and other host products and responses may influence a variety of important disease pathways, including atherosclerosis, mucosal inflammation, and premature parturition . The purpose of this article is to review the possible biological pathways by which periodontal diseases may influence these disease processes. Can J Microbiol, 2004 Sep, 50(9), 683 - 90 Role of MetR and PurR in the activation of glyA by CsgD in Escherichia coli K-12; Chirwa NT et al.; The csgD gene of Escherichia coli is required for the expression of curli fibres, surface fibres that are important for biofilm formation and infection . Previously, we demonstrated that expression of CsgD from a multicopy plasmid increased expression of the glyA gene, which codes for serine hydroxymethyltransferase . We show here that this activation requires the participation of both known regulatory proteins, MetR and PurR . The adjacent divergently transcribed gene hmp was weakly induced by CsgD, but its induction did not require MetR or PurR . The effect of CsgD on the expression of several pur and met genes was also tested. J Environ Manage, 2005 Feb, 74(3), 255 - 63 Epub 2004 Dec 15. Effects of inorganic nutrients on the regrowth of heterotrophic bacteria in drinking water distribution systems; Chu C et al.; Three laboratory-scale water pipe systems were set up to study the effects of adding three inorganic nutrients (ammonium, nitrate or phosphate) on biofilm formation in water pipes . The results showed that the effects of adding ammonium or nitrate on the biofilm formation were insignificant when levels below 0.1mg N/l were added . Analogous results were observed when phosphate was added at levels below 0.005mgP/l . However, as the addition of ammonium increased to 0.5mgN/l, significant effects on biofilm formation were observed . Similar results were obtained phosphate was added at levels above 0.01mgP/l . Batch tests were also conducted using water samples collected from a Taiwanese drinking water distribution system . The results indicated that the addition of ammonium, nitrate or phosphate to treatment plant effluent stimulates bacterial growth . In the distributed water of an urban area, the addition of nitrate or phosphate stimulated bacterial growth . The bacterial growth in the distributed water of a suburban area was not stimulated by adding any of these three inorganic nutrients. J Environ Manage, 2005 Feb, 74(3), 245 - 53 Epub 2004 Dec 15. A simplified model for the steady-state biofilm-activated sludge reactor; Fouad M et al.; A simplified mathematical model is proposed to describe the steady-state completely mixed biofilm-activated sludge reactor (hybrid reactor) . The model is derived based on Monod kinetic expressions and the Fickian diffusion law in biofilm . In addition, it considers all the essential concepts that describe the two types of growth (suspended and attached) and the competition between them for limiting substrate . Also the present study has been extended to investigate simple and accurate mathematical expressions for describing the substrate diffusion in biofilm (J) . The expression for substrate flux has an explicit solution, which may be useful in the proposed model and many other applications . The application of the model for the hybrid system has been explained for a given set of data and verified by comparison with another solution . Also the model was applied to experimental results for a trace level of suspended biomass concentration (X) . It was found that the biofilm flux (J) is the key factor in the model prediction, hence the accuracy of the model output is influenced by the accuracy of J . Compared with other solutions for such systems the model is simple, easy to use, and provides an accurate tool for describing such systems based on fundamental principles. Water Res, 2005 Jan-Feb, 39(2-3), 478 - 86 Action of a cationic surfactant on the activity and removal of bacterial biofilms formed under different flow regimes; Simoes M et al.; The action of the cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated to control biofilms (aged 7d) formed by Pseudomonas fluorescens on stainless-steel slides, using flow cells reactors, under turbulent and laminar flow . The effect of CTAB was also investigated using planktonic cells in the presence and absence of BSA, by measuring the cellular respiratory activity and the ATP released . The action of CTAB on biofilms was assessed by means of cellular respiratory activity and variation of biofilm mass, immediately and 3, 7 and 12h after the application of CTAB . The physical stability of the biofilm was also assessed using a rotating device, where the effect of the surfactant on the biofilm stability was evaluated through the variation of the mass remaining on the surface . CTAB significantly reduced the activity of the planktonic cells probably due to the rupture of the cells . This effect was significantly reduced in the presence of BSA . Planktonic cells were more easily inactivated than bacteria in biofilms . Biofilms formed under laminar flow were more susceptible than those formed under turbulent flow, but in both cases total inactivation was not achieved . Biofilm recovery was observed, in terms of respiratory activity, in almost all the cases studied . CTAB application by itself did not promote the detachment of biofilms . The physical stability tests showed that the synergistic action of the surfactant and the application of high shear stress to the biofilm increase its detachment. Water Res, 2005 January - February, 39(2-3), 380 - 388 Epub 2004 Dec 8. Analysis of bacterial diversity in river biofilms using 16S rDNA PCR-DGGE: methodological settings and fingerprints interpretation; Lyautey E et al.; Reliability of bacterial diversity assessment using polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) analysis of 16S rDNA fragments was evaluated for a particular complex microbial assemblage: river epilithic biofilm . By comparing 3 routine protocols on replicates of one river biofilm sample, we found that common DNA extraction procedures gave comparable diversity (from 28.0 to 30.7 bands detected) and community composition (> 75% of homology) despite differences in the total amount of extracted DNA (from 0.9 to 4.2mug) . Therefore methodological improvements only concerned electrophoretic separation of DNA fragments (range of denaturing gradient from 35% to 70% and migration time=18h) and standardisation of DNA amounts used (PCR-template=50ng, gel loading=700ng) . Using such a standardised methodology we found a good reproducibility of all steps of the procedure . When an Escherichia coli strain was introduced as a contaminant in a biofilm sample, we were able to recover ribotypes from the strain . As concerns fields sampling, a satisfactory repeatability of banding patterns from neighbouring pebbles (sampling point) allowed discriminating between the biofilm intrasite variability (various points from a cross-profile) . These trials confirmed that PCR-DGGE is suitable to assess a reliable genetic fingerprint of epilithic biofilms in the river . Phylogenetic analysis of 40 partial sequences of 16S rDNA from DGGE gels of two sets of river biofilms samples proved evidences for the retrieval of DNA fragments related to phototroph Eukarya . However, in both cases plastidial 16S rDNA represented less than 25% of the analysed operational taxonomic units . Taking into account that Cyanobacteria, as members of the Bacteria, were also detected, sequence analysis of relevant bands from the pattern is required to target "bacteria", i.e . the functional group of prokaryotic microorganisms to which one commonly refers as a key component in sustaining the nutrient turnover. Environ Microbiol, 2005 Jan, 7(1), 13 - 21 The effect of cleaning and disinfecting the sampling well on the microbial communities of deep subsurface water samples; Basso O et al.; Summary Our knowledge of the microbial characteristics of deep subsurface waters is currently very limited, mainly because of the methods used to collect representative microbial samples from such environments . In order to improve this procedure, a protocol designed to remove the unspecific, contaminant biofilm present on the walls of an approximately 800 m deep well is proposed . This procedure included extensive purges of the well, a mechanical cleaning of its wall, and three successive chlorine injections to disinfect the whole line before sampling . Total bacterial counts in water samples decreased from 2.5 x 10(5) to 1.0 x 10(4) per millilitre during the cleaning procedure . Culture experiments showed that the first samples were dominated by sulfate-reducers and heterotrophs, whereas the final sample was dominated by oligotrophic and hydrogenotrophic bacteria . Community structures established on the diversity of the 16S rRNA genes and data analysis revealed that the water sample collected, after a purge without removal of the biofilm, was characterized by numerous phyla which are not representative of the deep subsurface water . On the other hand, several bacterial phyla were only detected after the full cleaning of the well, and were considered as important components of the subsurface ecosystem which would have been missed in the absence of well cleaning. Clin Diagn Lab Immunol, 2005 Jan, 12(1), 93 - 100 Inhibition of Biofilm Formation by Monoclonal Antibodies against Staphylococcus epidermidis RP62A Accumulation-Associated Protein; Sun D et al.; Staphylococcus epidermidis expresses a 140-kDa cell wall-bound protein accumulation-associated protein (AAP) to adhere to and accumulate as a biofilm on a surface . Potentially blocking AAP with a monoclonal antibody (MAb) could reduce or eliminate S . epidermidis bacterial colonization of biomedical devices . Here, we report on our efforts to (i) isolate AAP, (ii) generate MAbs against AAP, and (iii) determine the efficacy of MAbs to inhibit S . epidermidis biofilm formation . An M7 S . epidermidis mutant, reportedly deficient in AAP expression, was used as a negative control . Postinoculation murine sera, containing polyclonal antibodies against AAP, were able to reduce S . epidermidis biofilm formation by 54% . Select MAbs against AAP were able to reduce S . epidermidis by no more than 66% . Two MAb mixtures, 12C6/12A1 and 3C1/12A1, reduced S . epidermidis accumulation up to 79 and 87%, respectively, significantly more than individual MAbs . Contrary to a previous report, biofilm-deficient S . epidermidis mutant M7 expressed a 200-kDa protein on its cell wall that specifically bound AAP MAbs . Peptide characterization of this M7 protein by microcapillary reversed-phase high-pressure liquid chromatography-nanoelectrospray tandem mass spectrometry resulted in 53% homology with AAP . Ongoing studies will elucidate the dynamic expression of AAP and the M7 200-kDa protein in order to define their roles in biofilm formation. Appl Environ Microbiol, 2005 Jan, 71(1), 507 - 11 Legionella species diversity in an acidic biofilm community in yellowstone national park; Sheehan KB et al.; Legionella species are frequently detected in aquatic environments, but their occurrence in extreme, acidic, geothermal habitats has not been explored with cultivation-independent methods . We investigated a predominately eukaryotic algal mat community in a pH 2.7 geothermal stream in Yellowstone National Park for the presence of Legionella and potential host amoebae . Our analyses, using PCR amplification with Legionella-specific primers targeting 16S rRNA genes, detected four known Legionella species, as well as Legionella sequences from species that are not represented in sequence databases, in mat samples and cultivated isolates . The nonrandom occurrence of sequences detected at lower (30 degrees C) and higher (35 to 38 degrees C) temperatures suggests that natural thermal gradients in the stream influence Legionella species distributions in this mat community . We detected only one sequence, Legionella micdadei, from cultivated isolates . We cultured and sequenced partial 18S rRNA gene regions from two potential hosts, Acanthamoeba and Euglena species. Appl Environ Microbiol, 2005 Jan, 71(1), 428 - 35 Use of fluorophore-conjugated lectins to study cell-cell interactions in model marine biofilms; Wigglesworth-Cooksey B et al.; Biofilms dominated by pennate diatoms are important in fields as diverse as ship biofouling and marine littoral sediment stabilization . The architecture of a biofilm depends on the fact that much of its mass consists of extracellular polymers . Although most illuminated biofilms in nature are dominated by phototrophs, they also contain heterotrophic bacteria . Given the close spatial association of the two types of organisms, cell-cell interaction is likely . Fluorophore-conjugated lectins were used to demonstrate the sites of the various extracellular polymers in three species of diatoms . Based on their lectin staining properties, the polymers in different species appeared to be similar, but their involvement in the process of attachment to a surface differed . In a coculture Pseudoalteromonas sp . strain 4 or its sterilized spent medium reduced the ability of Amphora coffeaeformis and Navicula sp . strains 1 and D to adhere, inhibited motility, and caused agglutination and eventually diatom cell lysis . Diatoms could be protected from the negative effects of the bacterial spent medium if d-galactose or mannan was included in the incubation medium . The active principle of the spent medium is probably a lectin/agglutinin that is able to bind to the extracellular polymers of the diatoms that are involved in adhesion and motility . Awareness of interactions of this type is important in the study of natural biofilms. Appl Environ Microbiol, 2005 Jan, 71(1), 354 - 62 Interactions between Oral Bacteria: Inhibition of Streptococcus mutans Bacteriocin Production by Streptococcus gordonii; Wang BY et al.; Streptococcus mutans has been recognized as an important etiological agent in human dental caries . Some strains of S . mutans also produce bacteriocins . In this study, we sought to demonstrate that bacteriocin production by S . mutans strains GS5 and BM71 was mediated by quorum sensing, which is dependent on a competence-stimulating peptide (CSP) signaling system encoded by the com genes . We also demonstrated that interactions with some other oral streptococci interfered with S . mutans bacteriocin production both in broth and in biofilms . The inhibition of S . mutans bacteriocin production by oral bacteria was stronger in biofilms than in broth . Using transposon Tn916 mutagenesis, we identified a gene (sgc; named for Streptococcus gordonii challisin) responsible for the inhibition of S . mutans bacteriocin production by S . gordonii Challis . Interruption of the sgc gene in S . gordonii Challis resulted in attenuated inhibition of S . mutans bacteriocin production . The supernatant fluids from the sgc mutant did not inactivate the exogenous S . mutans CSP as did those from the parent strain Challis . S . gordonii Challis did not inactivate bacteriocin produced by S . mutans GS5 . Because S . mutans uses quorum sensing to regulate virulence, strategies designed to interfere with these signaling systems may have broad applicability for biological control of this caries-causing organism. Appl Environ Microbiol, 2005 Jan, 71(1), 247 - 54 Biofilm Formation by Escherichia coli O157:H7 on Stainless Steel: Effect of Exopolysaccharide and Curli Production on Its Resistance to Chlorine; Ryu JH et al.; The resistance of Escherichia coli O157:H7 strains ATCC 43895-, 43895-EPS (an exopolysaccharide {EPS}-overproducing mutant), and ATCC 43895+ (a curli-producing mutant) to chlorine, a sanitizer commonly used in the food industry, was studied . Planktonic cells of strains 43895-EPS and/or ATCC 43895+ grown under conditions supporting EPS and curli production, respectively, showed the highest resistance to chlorine, indicating that EPS and curli afford protection . Planktonic cells (ca . 9 log(10) CFU/ml) of all strains, however, were killed within 10 min by treatment with 50 mug of chlorine/ml . Significantly lower numbers of strain 43895-EPS, compared to those of strain ATCC 43895-, attached to stainless steel coupons, but the growth rate of strain 43895-EPS on coupons was not significantly different from that of strain ATCC 43895-, indicating that EPS production did not affect cell growth during biofilm formation . Curli production did not affect the initial attachment of cells to coupons but did enhance biofilm production . The resistance of E . coli O157:H7 to chlorine increased significantly as cells formed biofilm on coupons; strain ATCC 43895+ was the most resistant . Population sizes of strains ATCC 43895+ and ATCC 43895- in biofilm formed at 12 degrees C were not significantly different, but cells of strain ATCC 43895+ showed significantly higher resistance than did cells of strain ATCC 43895- . These observations support the hypothesis that the production of EPS and curli increase the resistance of E . coli O157:H7 to chlorine. Appl Environ Microbiol, 2005 Jan, 71(1), 39 - 45 Bacillus subtilis {alpha}-Phosphoglucomutase Is Required for Normal Cell Morphology and Biofilm Formation; Lazarevic V et al.; Mutations designated gtaC and gtaE that affect alpha-phosphoglucomutase activity required for interconversion of glucose 6-phosphate and alpha-glucose 1-phosphate were mapped to the Bacillus subtilis pgcA (yhxB) gene . Backcrossing of the two mutations into the 168 reference strain was accompanied by impaired alpha-phosphoglucomutase activity in the soluble cell extract fraction, altered colony and cell morphology, and resistance to phages phi29 and rho11 . Altered cell morphology, reversible by additional magnesium ions, may be correlated with a deficiency in the membrane glycolipid . The deficiency in biofilm formation in gtaC and gtaE mutants may be attributed to an inability to synthesize UDP-glucose, an important intermediate in a number of cell envelope biosynthetic processes. Trends Microbiol, 2005 Jan, 13(1), 34 - 40 Survival strategies of infectious biofilms; Fux CA et al.; Modern medicine is facing the spread of biofilm-related infections . Bacterial biofilms are difficult to detect in routine diagnostics and are inherently tolerant to host defenses and antibiotic therapies . In addition, biofilms facilitate the spread of antibiotic resistance by promoting horizontal gene transfer . We review current concepts of biofilm tolerance with special emphasis on the role of the biofilm matrix and the physiology of biofilm-embedded cells . The heterogeneity in metabolic and reproductive activity within a biofilm correlates with a non-uniform susceptibility of enclosed bacteria . Recent studies have documented similar heterogeneity in planktonic cultures . Nutritional starvation and high cell density, two key characteristics of biofilm physiology, also mediate antimicrobial tolerance in stationary-phase planktonic cultures . Advances in characterizing the role of stress response genes, quorum sensing and phase variation in stationary-phase planktonic cultures have shed new light on tolerance mechanisms within biofilm communities. Trends Microbiol, 2005 Jan, 13(1), 27 - 33 Sociomicrobiology: the connections between quorum sensing and biofilms; Parsek MR et al.; In the past decade, significant debate has surrounded the relative contributions of genetic determinants versus environmental conditions to certain types of human behavior . While this debate goes on, it is with a certain degree of irony that microbiologists studying aspects of bacterial community behavior face the same questions . Information regarding two social phenomena exhibited by bacteria, quorum sensing and biofilm development, is reviewed here . These two topics have been inextricably linked, possibly because biofilms and quorum sensing represent two areas in which microbiologists focus on social aspects of bacteria . We will examine what is known about this linkage and discuss areas that might be developed . In addition, we believe that these two aspects of bacterial behavior represent a small part of the social repertoire of bacteria . Bacteria exhibit many social activities and they represent a model for dissecting social behavior at the genetic level . Therefore, we introduce the term 'sociomicrobiology'. Trends Microbiol, 2005 Jan, 13(1), 20 - 6 Biofilms: the matrix revisited; Branda SS et al.; Microbes often construct and live within surface-associated multicellular communities known as biofilms . The precise structure, chemistry and physiology of the biofilm all vary with the nature of its resident microbes and local environment . However, an important commonality among biofilms is that their structural integrity critically depends upon an extracellular matrix produced by their constituent cells . Extracellular matrices might be as diverse as biofilms, and they contribute significantly to the organization of the community . This review discusses recent advances in our understanding of the extracellular matrix and its role in biofilm biology. Trends Microbiol, 2005 Jan, 13(1), 16 - 9 Finding gene-expression patterns in bacterial biofilms; Beloin C et al.; The production of biofilms by bacteria is a lifestyle that is thought to require or involve a differential gene expression compared with that of planktonic bacteria . Recently, we have witnessed a change of focus from the simple hunt for hypothetical essential biofilm genes to the identification of late and more complex biofilm functions . However, finding common bacterial biofilm gene-expression patterns through global expression analysis remains difficult . Owing to the apparently minimal overlap between functions involved in biofilm formation by different bacteria, exploring the biofilm lifestyle could prove to be a case-by-case task for which global approaches show their limits. Trends Microbiol, 2005 Jan, 13(1), 11 - 5 Genome-genome interactions: bacterial communities in initial dental plaque; Kolenbrander PE et al.; The usual context for genome-genome interactions is DNA-DNA interactions, but the manifestation of the genome is the cell . Here we focus on cell-cell interactions and relate them to the process of building multi-species biofilm communities . We propose that dental plaque communities originate as a result of intimate interactions between cells (genomes) of different species and not through clonal growth of genetically identical cells . Although DNA exchange might occur between cells within these communities, we limit our opinions to discussions of the spatiotemporal and metabolic relationships that exist here . We believe the multi-species interactions occurring during the early stages of biofilm formation determine the species composition and nature of the mature biofilm . The human oral cavity provides easy access to natural biofilms on a retrievable enamel chip, which is an excellent model for the study of genome-genome interactions. Trends Microbiol, 2005 Jan, 13(1), 7 - 10 Biofilm formation and dispersal and the transmission of human pathogens; Hall-Stoodley L et al.; Several pathogenic bacterial species that are found in the environment can form complex multicellular structures on surfaces known as biofilms . Pseudomonas aeruginosa, Vibrio cholerae and certain species of nontuberculous mycobacteria are examples of human pathogens that form biofilms in natural aquatic environments . We suggest that the dynamics of biofilm formation facilitates the transmission of pathogens by providing a stable protective environment and acting as a nidus for the dissemination of large numbers of microorganisms; both as detached biofilm clumps and by the fluid-driven dispersal of biofilm clusters along surfaces . We also suggest that emerging evidence indicates that biofilm formation conveys a selective advantage to certain pathogens by increasing their ability to persist under diverse environmental conditions. Trends Microbiol, 2005 Jan, 13(1), 3 - 6 Quorum sensing in streptococcal biofilm formation; Suntharalingam P et al.; Bacteria in their natural ecosystems preferentially grow as polysaccharide-encased biofilms attached to surfaces . Although quorum-sensing (QS) systems directing the 'biofilm phenotype' have been extensively described in Gram-negative bacteria, there is little understanding of the importance of these systems in Gram-positive biofilm formation . Streptococci are a diverse group of Gram-positive bacteria that colonize epithelial, mucosal and tooth surfaces of humans . In several streptococci, competence-stimulating peptide (CSP)-mediated QS has been connected with competence development for genetic transformation . Recent work, especially with bacteria that inhabit the biofilm of dental plaque, has linked CSP stimuli to other cell-density adaptations, such as biofilm formation. Ann Clin Microbiol Antimicrob . 2005 Jan 7;4(1):2 {Epub ahead of print} In vitro activity of vancomycin, quinupristin/dalfopristin, and linezolid against intact and disrupted biofilms of staphylococci; El-Azizi M et al.; BACKGROUND: Shed cells or disrupted parts of the biofilm may enter the circulation causing serious and very hard to treat biofilm-associated infections . The activity of antimicrobial agents against the shed cells/disrupted biofilms is largely unknown . METHODS: We studied the in vitro susceptibility of intact and disrupted biofilms of thirty clinical isolates of methicillin-resistant and methicillin-susceptible Staphylococcus aureus (MRSA and MSSA) and Staphylococcus epidermidis to vancomycin, quinupristin/dalfopristin, and linezolid and compared it to that of the suspended (planktonic) cells . RESULTS: Bacteria in the disrupted biofilms were as resistant as those in the intact biofilms at the minimum inhibitory concentrations of the antibiotics . At higher concentrations, bacteria in the disrupted biofilms were significantly (P<0.001) less resistant than those in the intact biofilms but more resistant than the planktonic cells . Quinupristin/dalfopristin showed the best activity against cells of the disrupted biofilms at concentrations above MICs and vancomycin, at 500 and 1,000 ug/ml, was significantly more active against the biofilms of MRSA and S . epidermidis CONCLUSION: The difficulty of treating biofilm-associated infections may be attributed not only to the difficulty of eradicating the biofilm focus but also to the lack of susceptibility of cells disrupted from the biofilm to antimicrobial agents. Compend Contin Educ Dent, 2004 Oct, 25(10 Suppl 1), 44 - 50 In vitro evaluation of the efficacy and safety of the intelliclean system: interproximal biofilm removal and dentin substrate wear; Yuen AF et al.; The ability of a novel integrated power toothbrush and liquid-toothpaste dispensing system, the IntelliClean System from Sonicare and Crest, to remove interproximal biofilm while being gentle on dentin was studied using two in vitro models . Interproximal biofilm removal was assessed via a complex multispecies biofilm grown on hydroxyapatite disks and then placed interproximally in a typodont section modeling a typical oral environment . The power toothbrush in the prototype integrated system was compared to a traditional rotating/oscillating power toothbrush, the Oral-B ProfessionalCare 7000, and a nonbrushing control through a series of 3 experiments with a total of 36 replicates per arm . The amount of interproximal plaque biofilm removed by the integrated system toothbrush was significantly greater than that removed by the rotating/oscillating toothbrush and by the nonbrushing control (P < .05) . In the second model, dentin substrate wear was measured using profilometry after the brushing of dentin sections (3 mm x 10 mm) for a period equivalent to 2 years of typical product use . Dentin wear associated with the use of the prototype integrated system with standard and whitening versions of the liquid toothpaste was compared to that of a rotating/oscillating power toothbrush and a manual toothbrush with the standard version of the prototype liquid toothpaste, with a total of 12 replicates per arm . The amount of dentin wear induced by the integrated system with either the standard or whitening liquid toothpaste was significantly less than the wear from the rotating/oscillating power toothbrush and the manual toothbrush with the standard liquid toothpaste (P < .05). Gen Dent, 2004 Nov-Dec, 52(6), 502 - 4 Effect of a dental unit waterline additive on resin bond strengths; von Fraunhofer JA et al.; The literature indicates that the addition of an antimicrobial mouthrinse to self-contained water systems in dental units will control biofilm and effluent contamination; however, reports have varied concerning the possible effects of such agents on adhesive dentistry bond strengths . This study evaluated shear bond strengths and the potential effects of a mouthrinse containing essential oils on cut tooth surfaces by grinding flat the buccal surface of extracted human teeth . Seven groups consisting of five teeth each were etched with 37% H3PO4 solution and rinsed with water or different dilutions of the mouthrinse . Each tooth was blotted dry before a film of adhesive resin was applied to the surface and photocured . A cylinder of composite was placed on the surface and photocured . Shear bond strength testing was performed using a universal test machine . The cut tooth surfaces were ground (using water or the test mouthrinse mixtures as coolant) and evaluated by scanning electron microscopy. Extremophiles, 2004 Dec, 8(6), 463 - 73 Epub 2004 Aug 05. Community structure and photosynthetic activity of epilithon from a highly acidic (pH</=2) mountain stream in Patagonia, Argentina; Baffico GD et al.; We explored a benthic community living on stones in an acidic (pH</=2) stream of active volcanic origin from Patagonia, Argentina, by combining in situ measurements (temperature, pH, conductivity, dissolved oxygen), photosynthesis of intact biofilms (measured with microsensors by the light-dark shift method), pure-culture experiments on isolated algae, and confocal laser scanning microscopy on the biofilms . The epilithon of the Agrio River was dominated (99% of total biomass) by one species: Gloeochrysis (Chrysophyceae) . This species was observed as brown, mucilaginous, 200-mum-thick films on stones, growing in clumps in a dense matrix of fungal hyphae, bacteria, and inorganic particles held together by extracellular polymeric substances . Gloeochrysis was isolated and cultivated . The photosynthetic rate measured at saturation irradiance was 120 mumol oxygen (mg chlorophyll a)(-1)h(-1) under laboratory conditions, and the saturation rate of photosynthesis by carbon dioxide was 90 mumol oxygen (mg chlorophyll a)(-1) h(-1) for oxygen evolution . Photosynthetic activity of the biofilm was light-dependent and saturated above 200 mumol photons m(-2) s(-1) . In the dark, the stone surface became anoxic . Our data suggest that primary production in the Agrio River was not limited by light, carbon, or phosphorus but instead, nitrogen-limited. Biol Pharm Bull, 2005 Jan, 28(1), 120 - 3 Contamination of Environmental Surfaces by Staphylococcus aureus in a Dermatological Ward and Its Preventive Measures; Oie S et al.; We investigated contamination of environmental surfaces by Staphylococcus aureus from April 1 to the end of June in 2002 in the dermatological ward (37 beds) of a university hospital . For surfaces contaminated by high levels of S . aureus, disinfection methods were evaluated . 100-10(5) colony forming units (cfu) of methicillin-resistant S . aureus (MRSA) or methicillin-sensitive S . aureus (MSSA) were detected on items such as an immersion bathtub (examined area, about 900 cm(2)), foot washbowl, stretcher for an immersion bath, and chair for the shower . After disinfection, no S . aureus was detected on smooth surfaces such as the immersion bathtub and foot washbowl; however, S . aureus was detected even after disinfection on porous surfaces made of sponge-like materials (polyethylene foam) such as the stretcher for the immersion bath and the shower chair . Scanning electron microscopy of the porous surfaces showed formation of a large amount of coccus and bacillus biofilms on the walls of pores in the multi-pore structure . Material that is porous should not be used in patient care settings because it is not possible to disinfect it properly. J Food Prot, 2004 Dec, 67(12), 2712 - 8 A predictive model for heat inactivation of Listeria monocytogenes biofilm on stainless steel; Chmielewski RA et al.; Heat treatment of potential biofilm-forming sites is sometimes used for control of Listeria monocytogenes in food processing plants . However, little information is available on the heat treatment required to kill L . monocytogenes present in biofilms . The purpose of this study was to develop a predictive model for the heat inactivation of L . monocytogenes in monoculture biofilms (strains Scott A and 3990) and in biofilms with competing bacteria (Pseudomonas sp . and Pantoea agglomerans) formed on stainless steel in the presence of food-derived soil . Biofilms were produced on stainless steel coupons with diluted tryptic soy broth incubated for 48 h at 25 degrees C . Duplicate biofilm samples were heat treated for 1, 3, 5, and 15 min at 70, 72, 75, 77, and 80 degrees C and tested for survivors using enrichment culture . The experiment was repeated six times . A predictive model was developed using logistic regression analysis of the fraction negative data . Plots showing the probability of L . monocytogenes inactivation in biofilms after heat treatment were generated from the predictive equation . The predictive model revealed that hot water sanitation of stainless steel can be effective for inactivating L . monocytogenes in a biofilm on stainless steel if time and temperature are controlled . For example, to obtain a 75% probability of total inactivation of L . monocytogenes 3990 biofilm, a heat treatment of 80 degrees C for 11.7 min is required . The model provides processors with a risk management tool that provides predicted probabilities of L . monocytogenes inactivation and allows a choice of three heat resistance assumptions . The predictive model was validated using a five-strain cocktail of L . monocytogenes in the presence of food soil. Microbiology, 2005 Jan, 151(Pt 1), 75 - 80 Modelling protection from antimicrobial agents in biofilms through the formation of persister cells; Roberts ME et al.; A mathematical model of biofilm dynamics was used to investigate the protection from antimicrobial killing that could be afforded to micro-organisms in biofilms based on a mechanism of 'persister' cell or phenotypic variant formation . The persister state is a hypothetical, highly protected state adopted by a small fraction of the cells in a biofilm . Persisters were assumed to be generated at a fixed rate, independent of the presence of substrate or antimicrobial agent . Cells were assumed to revert from the persister state when exposed to the growth substrate . Persister cells were assumed to be incapable of growth . The model predicted that persister cells increased in numbers in the biofilm, even though they were unable to grow, accumulating in regions of substrate limitation . In these regions, normal cells failed to grow, but did slowly convert to the persister state . Calculations of persister formation in planktonic cultures predicted that persisters would be present in low numbers in growing cultures, but should accumulate under conditions of slow growth, e.g . very low dilution rates in continuous culture or stationary phase in batch culture . When antibiotic treatment was simulated, bacteria near the biofilm surface were killed, but persisters in the depth of the biofilm were poorly killed . After antibiotic treatment ceased, surviving persister cells quickly reverted and allowed the biofilm to regrow . This modelling study provides motivation for further investigation of the hypothetical persister cell state as an explanation for biofilm resistance to antimicrobial agents. Drugs, 2005, 65(2), 179 - 214 Infections associated with medical devices : pathogenesis, management and prophylaxis; von Eiff C et al.; The insertion or implantation of foreign bodies has become an indispensable part in almost all fields of medicine . However, medical devices are associated with a definitive risk of bacterial and fungal infections . Foreign body-related infections (FBRIs), particularly catheter-related infections, significantly contribute to the increasing problem of nosocomial infections . While a variety of micro-organisms may be involved as pathogens, staphylococci account for the majority of FBRIs . Their ability to adhere to materials and to promote formation of a biofilm is the most important feature of their pathogenicity . This biofilm on the surface of colonised foreign bodies is regarded as the biological correlative for the clinical experience with FBRI, that is, that the host defence mechanisms often seem to be unable to handle the infection and, in particular, to eliminate the micro-organisms from the infected device . Since antibacterial chemotherapy is also frequently not able to cure these infections despite the use of antibacterials with proven in vitro activity, removal of implanted devices is often inevitable and has been standard clinical practice . However, in specific circumstances, such as infections of implanted medical devices with coagulase-negative staphylococci, a trial of salvage of the device may be justified . All FBRIs should be treated with antibacterials to which the pathogens have been shown to be susceptible . In addition to systemic antibacterial therapy, an intraluminal application of antibacterial agents, referred to as the 'antibiotic-lock' technique, should be considered to circumvent the need for removal, especially in patients with implanted long-term catheters.To reduce the incidence of intravascular catheter-related bloodstream infections, specific guidelines comprising both technological and nontechnological strategies for prevention have been established . Quality assurance, continuing education, choice of the catheter insertion site, hand hygiene and aseptic techniques are aspects of particular interest . Furthermore, all steps in the pathogenesis of biofilm formation may represent targets against which prevention strategies may be directed . Alteration of the foreign body material surface may lead to a change in specific and nonspecific interactions with micro-organisms and, thus, to a reduced microbial adherence . Medical devices made out of a material that would be antiadhesive or at least colonisation resistant would be the most suitable candidates to avoid colonisation and subsequent infection . Another concept for the prevention of FBRIs involves the impregnation of devices with various substances such as antibacterials, antiseptics and/or metals . Finally, further studies are needed to translate the knowledge on the mechanisms of biofilm formation into applicable therapeutic and preventive strategies. Appl Microbiol Biotechnol, 2005 Feb, 66(5), 567 - 74 Epub 2004 Oct 12. Continuous acetonitrile degradation in a packed-bed bioreactor; Manolov T et al.; A 20-l packed-bed reactor filled with foamed glass beads was tested for the treatment of acetonitrile HPLC wastes . Aeration was provided by recirculating a portion of the reactor liquid phase through an aeration tank, where the dissolved oxygen concentration was kept at 6 mg/l . At a feeding rate of 0.77 g acetonitrile l(-1) reactor day(-1), 99% of the acetonitrile was removed; and 86% of the nitrogen present in acetonitrile was released as NH(3), confirming that acetonitrile volatilization was not significant . Increasing the acetonitrile loading resulted in lower removal efficiencies, but a maximum removal capacity of 1.0 g acetonitrile l(-1) reactor day(-1) was achieved at a feeding rate of 1.6 g acetonitrile l(-1) reactor day(-1) . The removal capacity of the system was well correlated with the oxygenation capacity, showing that acetonitrile removal was likely to be limited by oxygen supply . Microbial characterization of the biofilm resulted in the isolation of a Comamonas sp . able to mineralize acetonitrile as sole carbon, nitrogen and energy source . This organism was closely related to C . testosteroni (91.2%) and might represent a new species in the Comamonas genus . This study confirms the potential of packed-bed reactors for the treatment of a concentrated mixture of volatile pollutants. J Bacteriol, 2005 Jan, 187(2), 639 - 48 The Erwinia chrysanthemi Type III Secretion System Is Required for Multicellular Behavior; Yap MN et al.; Enterobacterial animal pathogens exhibit aggregative multicellular behavior, which is manifested as pellicles on the culture surface and biofilms at the surface-liquid-air interface . Pellicle formation behavior requires production of extracellular polysaccharide, cellulose, and protein filaments, known as curli . Protein filaments analogous to curli are formed by many protein secretion systems, including the type III secretion system (TTSS) . Here, we demonstrate that Erwinia chrysanthemi, which does not carry curli genes, requires the TTSS for pellicle formation . These data support a model where cellulose and generic protein filaments, which consist of either curli or TTSS-secreted proteins, are required for enterobacterial aggregative multicellular behavior . Using this assay, we found that hrpY, which encodes a two-component system response regulator homolog, is required for activity of hrpS, which encodes a sigma(54)-dependent enhancer-binding protein homolog . In turn, hrpS is required for activity of the sigma factor homolog hrpL, which activates genes encoding TTSS structural and secreted proteins . Pellicle formation was temperature dependent and pellicles did not form at 36 degrees C, even though TTSS genes were expressed at this temperature . We found that cellulose is a component of the E . chrysanthemi pellicle but that pellicle formation still occurs in a strain with an insertion in a cellulose synthase subunit homolog . Since the TTSS, but not the cellulose synthase subunit, is required for E . chrysanthemi pellicle formation, this inexpensive assay can be used as a high throughput screen for TTSS mutants or inhibitors. J Bacteriol, 2005 Jan, 187(2), 611 - 8 Functional Dissection of a Conserved Motif within the Pilus Retraction Protein PilT; Aukema KG et al.; PilT is a hexameric ATPase required for type IV pilus retraction in gram-negative bacteria . Retraction of type IV pili mediates intimate attachment to and signaling in host cells, surface motility, biofilm formation, natural transformation, and phage sensitivity . We investigated the in vivo and in vitro roles of each amino acid of the distinct, highly conserved C-terminal AIRNLIRE motif in PilT . Substitution of amino acids A288, I289, L292, and I293 as well as a double substitution of R290 and R294 abolished Pseudomonas aeruginosa PilT function in vivo, as measured by a loss of surface motility and phage sensitivity . When introduced into purified Aquifex aeolicus PilT, substitutions in the AIRNLIRE motif did not disrupt ATPase activity or oligomerization . In contrast, a K136Q substitution in the broadly conserved nucleotide binding motif prevented PilT function in vivo as well as in vitro . We propose that the AIRNLIRE motif forms an amphipathic alpha helix which transmits signals between a surface-exposed protein interaction site and the ATPase core of PilT, and we recognize a potential functional homology in other type II secretion ATPases. Peptides, 2005 Feb, 26(2), 269 - 75 RNAIII-inhibiting peptide improves efficacy of clinically used antibiotics in a murine model of staphylococcal sepsis; Giacometti A et al.; RNAIII-inhibiting peptide (RIP, YSPWTNF-NH(2)) is a quorum-sensing peptide inhibitor that prevents Staphylococcus aureus toxin production and biofilm formation . A mouse sepsis model was used to test the efficacy of RIP alone or in combination with conventional antibiotics in suppressing S . aureus-induced sepsis . Mice were injected intravenously with 3.0x10(6)CFU of S . aureus ATCC 25923 or with 3.0x10(6)CFU of S . aureus strain Smith diffuse . All animals were randomized to receive intravenously isotonic sodium chloride solution as a control, or 20mg/kg RIP alone or combined with 20mg/kg cefazolin, 10mg/kg imipenem, or 10mg/kg vancomycin immediately or 6h after bacterial challenge . Main outcome measures were bacteremia and lethality . All compounds reduced lethality when compared to controls . Although, in general combined-treated groups had significant lower bacterial counts when associated to singly-treated groups only the combination between RIP and vancomycin with respect to cefazolin gave a statistically significant decrease in the lethality rate . Lowest lethality rates (10%) and bacteremia (<10(2)CFU/ml) were obtained when RIP was administered in combination with vancomycin . Because RIP can be synergistic with current antibiotic therapies and help to reduce S . aureus exotoxins production, it can be considered a promising agent to associate with antibiotics for further clinical research into treatment of sepsis. Blood Purif, 2005, 23(1), 23 - 8 Saving infected catheters: why and how; Allon M; Conventional management of dialysis catheter-related bacteremia involves administration of systemic antibiotics, as well as removal of the infected catheter . This approach adds burdensome and expensive procedures, and creates short-term problems for dialysis access . Recent research has shown that bacterial biofilms form routinely in the catheter lumen, and act as the nidus for bacteremic episodes . Instillation of a concentrated antibiotic-anticoagulant solution into the catheter lumen ('antibiotic lock') may permit successful treatment of the infection, while salvaging the patient's catheter . A number of recent studies have reported the success of an antibiotic lock protocol in about two thirds of cases of catheter-related bacteremia . Catheter replacement is only performed in those patients with protocol failures (persistent fever or positive surveillance blood cultures) . In conclusion, routine application of an antibiotic lock protocol may reduce substantially the need for routine catheter replacement in hemodialysis patients with catheter-related bacteremia . Copyright (c) 2005 S . Karger AG, Basel. Biochemistry (Mosc), 2004 Nov, 69(11), 1268 - 75 Cell-cell interactions in bacterial populations; Voloshin SA et al.; In developing bacterial populations many essential processes, such as division, genetic transformation, sporulation, and synthesis of antibiotics and secondary metabolites, are regulated by intercellular communication mediated by secretion of signaling molecules, such as homoserine lactones and peptides . Another intercellular communication type, namely a physical contact between cells (cell aggregation), plays a key role in formation of biofilms or cellular consortia and in cell proliferation under unfavorable conditions . The mechanisms involved in these two types of bacterial communication are discussed in this review. Spine, 2005 Jan 1, 30(1), 38 - 43 Adherence and biofilm formation of Staphylococcus epidermidis and Mycobacterium tuberculosis on various spinal implants; Ha KY et al.; STUDY DESIGN: Bacterial adherence and biofilm formation in implant-associated infection may vary depending on species of microorganisms and characteristics of implant surfaces . OBJECTIVES: We evaluated the differences in adherence and biofilm formation between Staphylococcus epidermidis and Mycobacterium tuberculosis on various spinal implant surfaces . SUMMARY OF BACKGROUND DATA: In implant-associated infections, bacteria in biofilm are resistant to antibiotics or host defense mechanism . The removal of implants is usually necessary to eradicate infection . On the contrary, in tuberculous infection, complete debridement and antituberculous chemotherapy without removal of implant have been regarded as a safe procedure . METHODS: S . epidermidis and M . tuberculosis were cultured with 4 types of metal segments, smooth or rough-surfaced stainless steel, and titanium alloy, respectively . After isolation of colonized microorganisms and biofilm with trypsin treatment and culture on plate media, colony-forming units were counted . The features of adherence and biofilm formation were observed under scanning electron microscopy . RESULTS: Biofilm-forming S . epidermidis showed heavy adhesion and multiplication on the surface of all 4 metal segments, 16.5 times more colony-forming units than nonbiofilm-forming ones . On scanning electron microscopy, there were many aggregated microcolonies with thick biofilm in biofilm-forming S . epidermidis but much less in nonbiofilm-forming S . epidermidis . M . tuberculosis were rarely adhered to metal surfaces and showed scanty biofilm formation . CONCLUSIONS: On the contrary to S . epidermidis, adherence and biofilm formation of M . tuberculosis on implant surface are less likely, and it can provide the basis of successful instrumentation in spine tuberculosis. Biol Trace Elem Res, 2004 Winter, 102(1-3), 129 - 42 Cytotoxicity of copper ions released from metal: variation with the exposure period and concentration gradients; Cortizo MC et al.; The aim of this work is to contribute to the elucidation of the cytotoxic process caused by the copper ions released from the biomaterials . Clonal cell lines UMR106 were used in the experiments . Copper ions were obtained from two different sources: copper salts and metal dissolution . Experiments carried out with constant ion concentrations (copper salts) were compared with those with concentrations that vary with time and location (dissolution of the metal) . Present results and others previously reported could be interpreted through mathematical models that describe: (1) the variation of concentration of copper ions with time and location within a biofilm and (2) the variation of the killing rate with the concentration of the toxic ion and time . The large number of dead cells found near the copper sample with an average ion concentration below the toxic limit could be interpreted bearing in mind that these cells should be exposed to a local concentration higher than this limit . A logarithmic dependence between the number of cells and exposure time was found for nearly constant ion concentrations . Apparent discrepancies, observed when these results and those of different researchers were contrasted, could be explained considering the dissimilar experimental conditions such as the source of the ions and their local concentration at real time. Biofouling, 2004 Aug-Oct, 20(4-5), 219 - 26 Evaluation of Hydrodynamic Drag on Experimental Fouling-release Surfaces, using Rotating Disks; Holm E et al.; Fouling by biofilms significantly increases frictional drag on ships' hulls . A device, the friction disk machine, designed to measure torque on rotating disks, was used to examine differences among experimental fouling-release coatings in the drag penalty due to accumulated biofilms . Penalties were measured as the percentage change in the frictional resistance coefficient C(f) . Drag penalties due to microfouling ranged from 9% to 29%, comparable to previously reported values . An antifouling control coating showed a smaller drag penalty than the fouling-release coatings . There were also significant differences among the fouling-release coatings in drag due to biofilm formation . These results indicate that the friction disk machine may serve as a valuable tool for investigating the effects of experimental coatings, both antifouling and fouling-release, on microfouling and associated drag penalties. Biofouling, 2004 Aug-Oct, 20(4-5), 189 - 201 Solute Size Effects on the Diffusion in Biofilms of Streptococcus mutans; Marcotte L et al.; The diffusion of poly(ethylene glycol) (PEG) (MW varying between 200 and 10,000), and of three different types of micelles was examined in Streptococcus mutans biofilms using infrared spectroscopy . PEGs were used because they show limited interactions with biological materials and their weight can be selected in order to cover a wide range of size . The study showed that a considerable fraction at the base of the biofilm was not accessible to the diffusing solute molecules and this inaccessible fraction was very dependent on the size of the diffusing molecules . In parallel, it was found that the diffusion coefficients of these solutes in the biofilms were less than those in water and this reduction was less pronounced for large macromolecules, an effect proposed to be related to their limited penetration . Triton X-100, a neutral detergent, forms micelles that behave like PEG, suggesting that the behaviour observed for neutral macromolecules can be extrapolated to neutral macroassemblies . However, the diffusion, as well as the penetration of sodium dodecylsulphate micelles (a negatively charged surfactant) and cetylpyridinium chloride micelles (positively charged), in the biofilms appeared to be significantly influenced by electrostatic interactions with biofilm components . The present findings provide useful insights associated with the molecular parameters required to efficiently penetrate bacterial biofilms . The study suggests a rationale for the limited bactericidal power of some antibiotics (the large ones) . The restricted accessibility of macromolecules and macroassemblies to biofilms must be examined carefully in order to offer guidelines in the development of novel antibacterial treatments. FEMS Microbiol Lett, 2005 Jan 15, 242(2), 345 - 351 Composition of in vitro denture plaque biofilms and susceptibility to antifungals; Lamfon H et al.; The aim of this study was to investigate the composition of microcosm denture plaque biofilms and the susceptibility of Candida spp . within these biofilms to antifungal agents . An in vitro model was employed to grow oral biofilms derived from denture associated stomatitis (DAS) patient samples to assess fungal growth in the presence and absence of antifungal agents . The compositions of genera present in vitro were found to be similar to those exhibited on the mucosa and denture fitting surfaces of DAS samples . Exposure to single agents, e.g., miconazole, fluconazole or chlorhexidine did not inhibit growth of Candida spp . when used in clinically relevant doses . Combinations of miconazole and chlorhexidine, pulsed into the system to mimic patient use, did reduce bacterial and candidal growth for several days . Hence, the use of dual-therapy appeared to be useful in reducing the number of viable organisms within denture plaque grown in vitro although resistance to these agents was also evident. Colloids Surf B Biointerfaces, 2005 Jan 15, 40(1), 45 - 9 Surface bio-magnetism on bacterial cells adhesion and surface proteins secretion; Chua LY et al.; Extensive research works have been done on using magnetic fields on biological organism, but the results till date have been controversial {D.O . Carpenter, S . Ayrapetyan (Eds.), Biological Effects of Electric and Magnetic Fields, vol . 1, Academic Press, San Diego, 1994} . In spite of this, the study of surface magnetic effects on bacterial adhesion and cell growth has not been rigorously explored . The effects of surface magnetism, using perpendicularly polarized magnetic media, are evaluated on Bacillus licheniformis, a widely used bacterium in brewery {L . Kandra, a-Amylases of medical and industrial importance . J . Mol . Struct . (Theochem.), in press} and pharmaceutical {H . Ikram-ul et al., Production of alph amylase by Bacillus licheniformis using an economical medium . Bioresour . Technol . 87 (2003) 57-61} industries, by observing its adhesion and growth behavior . At different spin directions, we are able to observe a change on the biofilm formation, protein synthesis, and cell growth rate . Given that surface energy can easily penetrate through cells, this approach is an advantage over existing techniques that require direct physical contact to target cells . It also presents a new technique to cell adhesion and synthesis of surface proteins. Int J Antimicrob Agents, 2005 Jan, 25(1), 44 - 50 Synergistic effect of fosfomycin and arbekacin on a methicillin-resistant Staphylococcus aureus-induced biofilm in a rat model; Morikawa K et al.; Biofilms are a major concern for clinicians in the treatment of infectious disease because of the resistance to a wide range of antibiotics . Using a rat air pouch model, methicillin-resistant Staphylococcus aureus (MRSA) growing as a biofilm was treated with a combination of fosfomycin (FOM) and arbekacin (ABK) or by the agents alone . This model has the advantage of permitting frequent sampling of exudates for bacterial counts and anti-bacterial activity, and morphological examination of the biofilm structure and inflammatory process in the pouch tissues . A clear synergistic effect was observed in the rats treated with a combination of fosfomycin and arbekacin . Morphological studies using scanning electron microscopy and histological staining showed dramatic changes of the biofilm structure as well as the inflammatory response in the rats . These results suggested an enhancement of bactericidal activity of arbekacin penetrating through the biofilm layer by virtue of fosfomycin . A possible mechanism of the synergistic effect is discussed. J Hosp Infect, 2005 Feb, 59(2), 159 - 62 High frequency of Candida parapsilosis on the hands of healthy hosts; Bonassoli LA et al.; The presence of yeasts on the hands of 86 healthy hosts (62 hospital workers and 24 healthy members of the community with no hospital exposure) was investigated . A high rate of colonization was found (59.3%) . Candida parapsilosis was the most frequently isolated species (51%), independent of the origin of the samples . The potential virulence and resistance to antifungals of the 26 C . parapsilosis isolates were determined . All were proteinase producers and formed biofilms . The haemolytic activity was variable, with a predominance of total haemolysis of sheep erythrocytes . All isolates were susceptible to amphotericin B but two showed reduced susceptibility to fluconazole . Healthy people may be colonized by a species of yeast with a high capacity for adhesion to plastic surfaces, providing an infection risk to susceptible individuals. Med Mal Infect, 2004 Nov, 34(11), 530 - 7 {Is bone infection of endogenous or exogenous origin? A pathophysiological approach}; Ader F et al.; Osteomyelitis is a bacterial implant in bone matrix . Infection occurs as a result of a bacteremia, an inoculation during aseptic or orthopedic surgery, or a contiguous infectious focus . Persistent and relapsing infection may be due to three situations: underlying conditions such as diabetes mellitus or rheumatoid arthritis, presence of foreign surgical implant, and a causative bacterial strain . The pathogenesis of osteomyelitis has been explored through various experimental models, involving mostly Staphylococcus (S . aureus, S . epidermidis) and has given new insights . Bacterial adherence to implanted devices or bone matrix via surface proteins is critical for bacterial survival . Further bacterial growth depends on various mechanisms: the capacity to exhibit matrix-embedded lifestyle known as biofilm and the ability for bacterial subpopulations to switch to a dormant metabolic state known as small colony variants . In addition to bacterial factors, the presence of foreign material induces a defect in local inflammatory response partly responsible for the high susceptibility to infection. Pesqui Odontol Bras, 2004 Jul-Sep, 18(3), 215 - 23 Comparative study of methods for the quantification of biofilm on complete dentures; Paranhos Hde F et al.; This study compared the application and reliability of 4 methods for biofilm quantification (computerized, paper-weighing, point-counting, and planimetric) in complete dentures, verifying the correlation between them . The internal surfaces of 62 complete dentures were stained (5% erythrosine) and photographed . The slides were projected on paper, and the areas (total and biofilm-covered) were outlined with a pencil . These areas were measured with an equidistant point grid (point-counting method), a digital planimeter (planimetric method), and for the paper weighing method they were cut and weighed with a precision scale . For the computerized method, ImageTool software was used . In order to perform a validation test of the methods, all of them were applied to slide projections of geometric figures with known dimensions . The correlation tests showed high correlation values (r = 0.82 to 0.99) among the methods . The validation test (ANOVA) showed no statistically significant differences among the values obtained from the measurement of figures using all four quantitative methods and the real dimensions of these geometric figures . Quantitative methods were efficient and reliable for measuring quantity of biofilm in complete dentures, and may be useful in experimental studies on the efficacy of hygiene products . The computerized method was fast and easy to perform. J Theor Biol, 2005 Mar 21, 233(2), 245 - 51 Porosity and tortuosity relations as revealed by a mathematical model of biofilm structure; Zacarias GD et al.; A biofilm is assumed to be submerged in a fluid with given viscosity and low Reynolds number . The interaction between fluid and bacteria is modeled through streamlines . We use finite-difference and boundary element numerical schemes to predict streamlines within the biofilm . The results show that this approach can provide information about prior distribution and geometry of the biofilm structure . Theoretical values of porosity and tortuosity are computed and compared with published data. Infect Immun, 2005 Jan, 73(1), 219 - 25 Trigger factor in Streptococcus mutans is involved in stress tolerance, competence development, and biofilm formation; Wen ZT et al.; Trigger factor is a ribosome-associated peptidyl-prolyl cis/trans isomerase that is highly conserved in most bacteria . A gene, designated ropA, encoding an apparent trigger factor homologue, was identified in Streptococcus mutans, the primary etiological agent of human dental caries . Inactivation of ropA had no major impact on growth rate in planktonic cultures under the conditions tested, although the RopA-deficient mutant formed long chains in broth . Deficiency of RopA decreased tolerance to acid killing and to oxidative stresses induced by hydrogen peroxide and paraquat, and it reduced transformation efficiency about 200-fold . Addition of synthetic competence-stimulating peptide to the culture medium enhanced transformability of both the mutant and wild-type strains, although the ropA strain did not attain levels of competence observed for the parent . Loss of RopA decreased the capacity of S . mutans to form biofilms by over 80% when cultivated in glucose, but it increased biofilm formation by over 50% when sucrose was provided as the carbohydrate source . Western blot analysis revealed that the expression of glucosyltransferases B and D was lower in the RopA-deficient mutant . These results suggest that RopA is a key regulator of acid and oxidative stress tolerance, genetic competence, and biofilm formation, all critical virulence properties of S . mutans. Environ Technol, 2004 Nov, 25(11), 1265 - 75 Sulphide and oxygen inhibition over the anaerobic digestion of organic matter: influence of microbial immobilization type; Celis-Garcia ML et al.; Two different types of microbial aggregates (granular sludge and biofilm onto a plastic matrix) were evaluated for their susceptibility to sulphide and dissolved oxygen . Their specific methanogenic and sulphate reducing activities were evaluated separately and simultaneously . Total sulphide concentrations that caused 50% loss of methanogenic activity were 800 and 1250 mg l(-1) and for sulphate reduction 750 and 860 mg l(-1) for the granular sludge and the attached biomass, respectively . Simultaneous methanogenesis and sulphate reduction resulted in an increased tolerance of the sulphate reducing process towards sulphide . Results suggest that methanogenesis in granular sludge is less resistant to sulphide than in the attached biomass structure, whereas in sulphate reduction the attached biomass exhibited a better tolerance to high concentrations of total sulphide than the granular sludge . The better sulphate reducing capacity in the attached biomass may suggest that biomass was selectively attached . The dissolved oxygen concentration that inhibited 50% the methanogenic activity was 4.9 and 6.4 mg l(-1) for the granular sludge and attached biomass, respectively . When methanogenesis and sulphate reduction were carried out simultaneously, the whole process was not affected by the supplied oxygen, as produced sulphide was used by sulphide oxidizing microorganisms thus scavenging oxygen . Results showed that the integration of anaerobic/aerobic conditions in a single bioreactor is quite possible and can be used as a good strategy for the complete transformation of sulphate to elemental sulphur. Antimicrob Agents Chemother, 2005 Jan, 49(1), 380 - 7 Real-time in vivo bioluminescent imaging for evaluating the efficacy of antibiotics in a rat Staphylococcus aureus endocarditis model; Xiong YQ et al.; Therapeutic options for invasive Staphylococcus aureus infections have become limited due to rising antimicrobial resistance, making relevant animal model testing of new candidate agents more crucial than ever . In the present studies, a rat model of aortic infective endocarditis (IE) caused by a bioluminescently engineered, biofilm-positive S . aureus strain was used to evaluate real-time antibiotic efficacy directly . This strain was vancomycin and cefazolin susceptible but gentamicin resistant . Bioluminescence was detected and quantified daily in antibiotic-treated and control animals with IE, using a highly sensitive in vivo imaging system (IVIS) . Persistent and increasing cardiac bioluminescent signals (BLS) were observed in untreated animals . Three days of vancomycin therapy caused significant reductions in both cardiac BLS (>10-fold versus control) and S . aureus densities in cardiac vegetations (P < 0.005 versus control) . However, 3 days after discontinuation of vancomycin therapy, a greater than threefold increase in cardiac BLS was observed, indicating relapsing IE (which was confirmed by quantitative culture) . Cefazolin resulted in modest decreases in cardiac BLS and bacterial densities . These microbiologic and cardiac BLS differences during therapy correlated with a longer time-above-MIC for vancomycin (>12 h) than for cefazolin ( approximately 4 h) . Gentamicin caused neither a reduction in cardiac S . aureus densities nor a reduction in BLS . There were significant correlations between cardiac BLS and S . aureus densities in vegetations in all treatment groups . These data suggest that bioluminescent imaging provides a substantial advance in the real-time monitoring of the efficacy of therapy of invasive S . aureus infections in live animals. Oral Microbiol Immunol, 2005 Feb, 20(1), 39 - 42 Synergy between Tannerella forsythia and Fusobacterium nucleatum in biofilm formation; Sharma A et al.; Sharma A, Inagaki S, Sigurdson W, Kuramitsu HK . Synergy betweenTannerella forsythia and Fusobacterium nucleatum in biofilm formation . Oral Microbiol Immunol 2005: 20: 39-42.(c) Blackwell Munksgaard, 2005 . During dental plaque formation, the interaction of different organisms is important in the development of complex communities . Fusobacterium nucleatum is considered a 'bridge-organism' that facilitates colonization of other bacteria by coaggregation-mediated mechanisms and possibly by making the environment conducive for oxygen intolerant anaerobes . These studies were carried out to determine whether coaggregation between F . nucleatum and Tannerella forsythia is important in the formation of mixed species biofilms . Further, the role of BspA protein, a surface adhesin of T . forsythia, in coaggregation and biofilm formation was investigated . The results showed the development of synergistic mixed biofilms of F . nucleatum and T . forsythia when these bacteria were cocultured . The BspA protein was not involved in biofilm formation . Though BspA plays a role in coaggregation with F . nucleatum, presumably other adhesins are also involved . The synergistic biofilm formation between the two species was dependent on cell-cell contact and soluble components of the bacteria were not required . This study demonstrates that there is a positive synergy between F . nucleatum and T . forsythia in the development of mixed biofilms and that the cell-cell interaction is essential for this phenomenon. Syst Appl Microbiol, 2004 Nov, 27(6), 728 - 36 Phylogenetic analysis of bacterial communities associated with larvae of the Atlantic halibut propose succession from a uniform normal flora; Jensen S et al.; Halibut, the largest of all flatfishes is a valuable species with a great potential for aquaculture . Bacteria play an important role in regulating the health of the early life stages . The present article is the first broad-range molecular analysis of bacterial communities in larvae of the Atlantic halibut (Hippoglossus hippoglossus) . DNA was extracted from larvae, water and silo biofilm from hatcheries in Norway, Scotland, Iceland and Canada . Eubacterial 16S rRNA gene fragments were amplified by polymerase chain reaction (PCR) with broad-range primers . Sequences spanning the hyper variable V3 region representing individual bacterial species were separated into community profiles by denaturing gradient gel electrophoresis (DGGE) . The profiles revealed simple communities after hatching and bacterial succession following growth . Sequencing and phylogenetic analysis of excised DGGE bands suggested aerobic heterotrophs related to groups of Pseudomonas, Janthinobacterium and possibly Marinomonas to be the primary colonisers of the larvae . After onset of feeding, fermentative species (Vibrio) were detected as well . Comparative analysis of bacterial communities from different geographical regions indicated that larvae of the Atlantic halibut possess a distinct and specific normal flora. Genetika, 2004 Nov, 40(11), 1445 - 56 {Biofilms as a mode of existence of bacteria in external environment and host body: the phenomenon, genetic control, and regulation systems of development}; Protozoan grazing and its impact upon population dynamics in biofilm communities; School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Manchester, UKAbstract s.a . huws, a.j . mcbain and p . gilbert . 2004.Aims: To determine the impact of protozoan grazing on the population dynamics of a multispecies bacterial biofilm community . Methods and Results: Grazing by Acanthamoeba castellanii and the ciliate Colpoda maupasi upon biofilm and planktonic communities, composed of Klebsiella pneumoniae, Pseudomonas fluorescens and Staphylococcus epidermidis was investigated . Biofilms were formed using glass coverslips, held in a carousel device, as substrata for biofilm formation or in glass flow cells . The predatory effects of the amoeba were generally confined to the biofilm, where grazing rates corresponded to losses from the biofilm equivalent to ca 30 000 biofilm cells cm(-2) h(-1), with the amoeba becoming an integral part of the community . C . maupasi reduced the thickness of mature multispecies biofilms at steady-state from 500 to <200 mum . Conclusions: We report that the presence of the protozoa A . castellanii and C . maupasi markedly influence population dynamics within defined biofilm communities . Significance and Impact of the Study: The current study dispels the popular opinion that biofilms are protected against predation by protozoa . A . castellanii clearly has the capacity to graze mixed biofilm communities and to become integrally associated with them, whereas the ciliate C . maupasi reduced biofilm thickness by up to 60%. J Infect Dis, 2005 Jan 15, 191(2), 289 - 98 Epub 2004 Dec 10. Genomewide Analysis of Gene Expression in Staphylococcus epidermidis Biofilms: Insights into the Pathophysiology of S . epidermidis Biofilms and the Role of Phenol-Soluble Modulins in Formation of Biofilms; Yao Y et al.; Many bacterial pathogens form cellular agglomerations known as biofilms, which considerably limit the success of both antibiotic treatment and the human immune defense . To gain insight into the pathophysiology of the leading nosocomial pathogen, Staphylococcus epidermidis, we analyzed the genome of biofilm-forming S . epidermidis, constructed a microarray representing its entire transcriptome, and performed expression profiling of an S . epidermidis biofilm . Gene-regulated processes in the biofilm led to a nonaggressive and protected form of bacterial growth with low metabolic activity, which is optimally suited to guarantee long-term survival during chronic infection . A class of peptides known as phenol-soluble modulins, which combine proinflammatory activity with a putative role in detachment of biofilms, evolved as potential key determinants controlling the switch between aggressive and quiescent modes of infection . Our data suggest that S . epidermidis adjusts its lifestyle to varying requirements during colonization and infection by means of an expansive change of gene expression . The observed physiological characteristics of the biofilm mode of growth--in particular, the contribution of surfactant-like peptides--might serve as a model for a variety of biofilm-forming pathogens. J Korean Med Sci, 2004 Dec, 19(6), 779 - 82 Phase variation of biofilm formation in Staphylococcus aureus by IS 256 insertion and its impact on the capacity adhering to polyurethane surface; Kiem S et al.; While ica gene of Staphylococcus epidermidis is known to undergo phase variation by insertion of IS256, the phenomenon in Staphylococcus aureus has not been evaluated . Six biofilm-positive strains were tested for the presence of biofilm-negative phase-variant strains by Congo red agar test . For potential phase-variant strains, pulsed-field gel electrophoresis was done to exclude the possibility of contamination . To investigate the mechanism of the biofilm-negative phase variation, PCR for each ica genes were done . Changes of ica genes detected by PCR were confirmed by southern hybridization, and their nucleotides were analyzed by DNA sequencing . Influence of ica genes and biofilm formation on capacity for adherence to biomedical material was evaluated by comparing the ability of adhering to polyurethane surface among a biofilm-negative phase-variant strain and its parent strain . A biofilm-negative phase-variant S . aureus strain was detected from 6 strains tested . icaC gene of the phase-variant strain was found to be inactivated by insertion of additional gene segment, IS256 . The biofilm-negative phase-variant strain showed lower adhering capacity to polyurethane than its parent strain . This study shows that phase variation of ica gene occurs in S . aureus by insertion of IS256 also, and this biofilm-negative phase variation reduces adhering capacity of the bacteria. Water Res, 2005 Jan, 39(1), 248 - 256 Influence of the redox condition dynamics on the removal efficiency of a laboratory-scale constructed wetland; Wiessner A et al.; A laboratory reactor planted with Juncus effusus treating an artificial wastewater was used to investigate the short-term and long-term variations and interactions in the redox conditions as well as the removal efficiency of C and the N turnover . The permanent circulation of the process water enabled the micro-gradient processes to be evaluated for an operating period of 20 months . Steady-state conditions were achieved throughout the operating period with high mean removal efficiencies of 92.7% total organic carbon, 82.0% ammonia and 97.6% nitrate . Daily variations in the redox state of the rhizosphere of a few hundred mV were observed, ranging from about -200 to oxidized conditions of about +200mV and driven by daylight . Variations in pH associated with changes in light and redox were linked to the dynamics of the fates of organic and inorganic carbon species . The ammonia removal processes were found to be firmly established, including for moderately reduced redox conditions with high efficiencies for E(h)>-50mV . The enrichment of ammonia (up to 13mgl(-1)) closely linked to the light, particularly during summertime, indicates the existence of hitherto unconsidered additional N turnover pathways in the rhizoplane involving N(2) produced by microbes or released by plants . C turnover was strongly related to the seasonal variation in illumination with minimum efficiencies during the dark season . In addition, it was characterized by oscillation with periods of approximately 1 month . The relationships found are dominant for biofilms on the rhizoplane and decisive for the removal efficiency of especially simple constructed and natural wetlands . The results highlight the importance of helophytes and their physiological specifics for removal processes. Appl Spectrosc, 2004 Nov, 58(11), 1295 - 301 Characterization of the diffusion of polyethylene glycol in Streptococcus mutans biofilms by Raman microspectroscopy; Marcotte L et al.; We used Raman microspectroscopy to investigate in situ the spatial distribution of the biomass in Streptococcus mutans biofilms . We used the CH stretching band to probe the organic matter and the area of the OH stretching band as an internal intensity standard, the biofilms being highly hydrated . The size of the biofilm regions that were mapped was 300 x 300 microm . We also recorded, in the confocal mode, the z profiles describing the biomass distribution as a function of depth in the biofilms . In our growth conditions, the biofilm is described as an approximately 75 microm thick mat completely covering the surface and includes columnar clusters with a diameter of approximately 100 microm surrounded by voids filled with water . Raman mapping was also used to examine the diffusion of HOD and polyethylene glycol with a molar mass of 10,000 (PEG-10k) in the biofilms . This study establishes that HOD can diffuse practically everywhere in the biofilms but that the penetration of PEG-10k is limited . There is a correlation between the restricted penetration of the macromolecule and the biomass content in the different regions of the biofilms . The method presented here provides a convenient approach to determine the diffusion of molecules, including antibacterials, in bacterial biofilms. Clin Microbiol Infect, 2004 Dec, 10(12), 1081 - 8 Presence of the ica operon in clinical isolates of Staphylococcus epidermidis and its role in biofilm production; Cafiso V et al.; Staphylococcus epidermidis is an important cause of catheter-associated infections, which are attributed to its ability to form a multilayered biofilm on polymeric surfaces . This ability depends, in part, on the activity of the icaADBC locus and the icaR gene, which are involved in the production of the polysaccharide intercellular adhesin (PIA) that is functionally necessary for cell-to-cell adhesion and biofilm accumulation . The present study determined: (1) the prevalence of the icaADBC operon in S . epidermidis isolates from catheter-related and other nosocomial infections; (2) the correlation between the presence of this operon, biofilm production and resistance to antibiotics; (3) the expression of ica genes and biofilm production; and (4) the genetic relatedness of the isolates . The results showed that icaRADBC was present in 45% of the isolates included in the study, and that such isolates were significantly more resistant to the main antibiotics tested than were ica-negative isolates . The presence of the entire cluster did not always correlate with biofilm production, determined under different culture conditions, but there was evidence to suggest a correlation when at least two genes (icaAD) were co-transcribed . Eight of 18 ica-positive isolates had the entire operon in the same restriction fragment after pulsed-field gel electrophoresis, but the isolates were not clonal . Estimation of genetic relatedness indicated that ica-positive S . epidermidis isolates belonged to different lineages, distributed in only one of two major clusters, with a genetic distance of c . 0.12. Biotechnol Lett, 2004 Nov, 26(21), 1653 - 7 Production of extracellular polymeric substances in anoxic/oxic process with zeolite carriers for nitrogen removal; Park SJ et al.; During the hydraulic retention time (HRT) from 12 to 6h, the production of extracellular polymeric substance (EPS) decreased from 82 to 70EPSmg volatile suspended solids (VSS) g(-1) in an anoxic/oxic (A/O) reactor with zeolite carriers . Added zeolite could successfully control the EPS production by the formation of stable biofilm and the maintenance the lower chemical oxygen demand/ammonium (C/N) ratio on its surface. Environ Sci Pollut Res Int, 2004, 11(6), 372 - 7 Decolorization and biodegradation of dye wastewaters by a facultative-aerobic process; Li Y et al.; BACKGROUND: Dye wastewater is one of the main pollution sources of water bodies in China . Conventional biological processes are relatively ineffective for color removal, the development of alternative treatment methods will become important . Our subjective was that of introducing a new biotreatment technology which combined a facultative biofilm reactor (FBR) with an aerobic reactor (AR) to treat a dye wastewater . The efficiencies of color and chemical oxygen demand (COD) removal and the mechanism of dye degradation were investigated . METHODS: The anthraquinone acid dye (acid blue BRLL) concentration, organic loading rate (OLR) and hydraulic retention time (HRT) were varied in the experiments to evaluate the treatment efficiency and process stability . The biodegradation products were detected by infrared (IR) and high performance liquid chromatography and mass spectrometry (HPLC-MS) . RESULTS AND DISCUSSION: The results demonstrated that the facultative biofilm process was more effective for decolorization than the anaerobic stage of an anaerobic-aerobic process . Most color removal occurred in the facultative reaction (maximum to 88.5%) and the BOD (biochemical oxygen demand): COD of the FBR effluent increased by 82.2%, thus improving the biodegradability of dyes for further aerobic treatment . The dye concentration, OLR and HRT will be the factors affecting decolorization . Color removal efficiency falls as the influent dye concentration increases, but rises with increased HRT . The infrared and HPLC-MS analyses of the effluents of FBR and AR reveal that the dye parent compound was degraded in each reactor during the process . CONCLUSION: The Facultative-aerobic (F-A) system can effectively remove both color and COD from the dye wastewater . The FBR played an essential role in the process . The average overall color and COD in the system were removed by more than 93.9% and 97.1%, respectively, at an OLR of 1.1 kg COD m(-3) d(-1) and at the HRT of 18-20 hours in the FBR and 4-5 hours in the AR . The color removal mechanism in each reactor was not only a sort of biosorption on the floc materials, but even more an effect of biodegradation, especially in the facultative process . Recommendation and Outlook . In applying the F-A system to treat a dye wastewater, the control of facultative processes and the set up of appropriate operation conditions appear to be critical factors . Also, it is suggested a moderate COD loading rate and about a 24-hour HRT will favor the F-A system. J Bacteriol, 2005 Jan, 187(1), 382 - 7 Depolymerization of beta-1,6-N-acetyl-D-glucosamine disrupts the integrity of diverse bacterial biofilms; Itoh Y et al.; Polymeric beta-1,6-N-acetyl-D-glucosamine (poly-beta-1,6-GlcNAc) has been implicated as an Escherichia coli and Staphylococcus epidermidis biofilm adhesin, the formation of which requires the pgaABCD and icaABCD loci, respectively . Enzymatic hydrolysis of poly-beta-1,6-GlcNAc, demonstrated for the first time by chromatography and mass spectrometry, disrupts biofilm formation by these species and by Yersinia pestis and Pseudomonas fluorescens, which possess pgaABCD homologues. J Bacteriol, 2005 Jan, 187(1), 37 - 44 Timing and localization of rhamnolipid synthesis gene expression in Pseudomonas aeruginosa biofilms; Lequette Y et al.; Pseudomonas aeruginosa biofilms can develop mushroom-like structures with stalks and caps consisting of discrete subpopulations of cells . Self-produced rhamnolipid surfactants have been shown to be important in development of the mushroom-like structures . The quorum-sensing-controlled rhlAB operon is required for rhamnolipid synthesis . We have introduced an rhlA-gfp fusion into a neutral site in the P . aeruginosa genome to study rhlAB promoter activity in rhamnolipid-producing biofilms . Expression of the rhlA-gfp fusion in biofilms requires the quorum-sensing signal butanoyl-homoserine lactone, but other factors are also required for expression . Early in biofilm development rhlA-gfp expression is low, even in the presence of added butanoyl-homoserine lactone . Expression of the fusion becomes apparent after microcolonies with a depth of >20 mum have formed and, as shown by differential labeling with rfp or fluorescent dyes, rhlA-gfp is preferentially expressed in the stalks rather than the caps of mature mushrooms . The rhlA-gfp expression pattern is not greatly influenced by addition of butanoyl-homoserine lactone to the biofilm growth medium . We propose that rhamnolipid synthesis occurs in biofilms after stalks have formed but prior to capping in the mushroom-like structures . The differential expression of rhlAB may play a role in the development of normal biofilm architecture. Mycoses, 2004 Dec, 47(11-12), 491 - 4 Frequency of intravascular catheter colonization by Malassezia spp . in adult patients; Curvale-Fauchet N et al.; Summary Colonization of intravascular catheters (IVCs) with lipid-dependent Malassezia spp . is rarely reported in adult patients probably because of the absence of additional lipids in routine culture media . Therefore, we systematically seeded 983 consecutive IVC onto Dixon medium compatible with the growth of Malassezia spp . Seven (0.7%) IVCs were positive . Six of them were from surgical patients . Four of them also yielded common bacteria . Identification using PCR-RFLP and restriction enzymes yielded M . furfur and M . sympodialis . Colonization of IVCs with Malassezia spp . does not appear negligible and warrants additional studies to evaluate the clinical relevance of such findings and the role of this yeast in biofilm formation . Zusammenfassung Uber die Besiedelung von intravaskularen Kathetern (IVC) mit Lipid-abhangigen Malassezia spp . wurde bei erwachsenen Patienten in der Fachliteratur bisher nur wenig berichtet . Dies konnte unter anderem darin begrundet sein, dass die herkommlichen Kulturmedien zur Erregeranzucht keinen besonderen Fettzusatz aufweisen . Daher beimpften wir bei 983 konsekutiven IVCs ein Dixon-Medium, das Wachstum von Malassezia spp . begunstigt . Bei sieben IVCs (0.7%) wurde Wachstum beobachtet . Speziesidentifizierung mittels PCR-RFLP und Restriktionsenzymverdauung ergab Malassezia furfur und Malassezia sympodialis . Sechs der untersuchten IVCs stammten dabei von chirurgischen Patienten . Bei vier der untersuchten IVCs wurde zusatzlich Wachstum von herkommlichen Bakterien beobachtet . Die Kolonisierung von IVCs mit Malassezia spp . erscheint daher nicht vernachlassigbar . Weitere Studien zur Evaluierung der klinischen Relevanz und der Rolle dieser Pilzspezies bei der Bildung von Biofilm sind daher angezeigt. Phys Rev Lett . 2004 Nov 5;93(19):198103 . Epub 2004 Nov 03. Anomalous fluid transport in porous media induced by biofilm growth; Seymour JD et al.; Magnetic resonance measurements of the transition from normal to anomalous hydrodynamic dispersion in porous media due to biological activity are presented . Fractional advection-diffusion equations are shown to provide models for the measured impact of biofilm growth on porous media transport dynamics. Bioinformatics . 2004 Dec 14; {Epub ahead of print} The G5 domain: a potential N-acetylglucosamine recognition domain involved in biofilm formation; Bateman A et al.; SUMMARY: Biofilms are complex microbial communities found at surfaces that are often associated with extracellular polysaccharides . Biofilm formation is a complex process that is only recently being understood at the molecular level . We have identified a novel domain that we call the G5 domain (named after its conserved glycine residues) which is found in a variety of enzymes such as Streptococcal IgA peptidases and various glycosyl hydrolases in bacteria . The G5 domain is found in the Accumulation Associated Protein (AAP) that is an important component in biofilm formation in Staphylococcus aureus . A common feature of the proteins containing G5 domains is N-acetylglucosamine binding, and we attribute this function to the G5 domain. FEMS Microbiol Lett, 2004 Dec 15, 241(2), 143 - 50 Isolation and characterization of a novel sphingomonad capable of growth with chrysene as sole carbon and energy source; Willison JC; A bacterial strain able to grow in pure culture with chrysene as sole added carbon and energy source was isolated from PAH-contaminated soil after successive enrichment cultures in a biphasic growth medium . Initially, growth occurred in the form of a biofilm at the interface between the aqueous and non-aqueous liquid phases . However, after a certain time, a transition occurred in the enrichment cultures, with growth occurring in suspension and a concomitant increase in the rate of chrysene degradation . The strain responsible for chrysene degradation in these cultures, named Sphingomonas sp . CHY-1, was identified by 16S rDNA sequencing as a novel sphingomonad, the closest relative in the databases being Sphingomonas xenophaga BN6(T) (96% sequence identity) . Both these strains clustered with members of the genera Sphingobium and Rhizomonas, but could not be categorically assigned to either genus . Sphingomonas sp . CHY-1 was characterized in terms of its growth on chrysene and other PAH, and the kinetics of chrysene degradation and (14)C-chrysene mineralization were measured . At an initial chrysene concentration of 0.5 gl(-1) silicone oil, and an organic/aqueous phase ratio of 1:4, chrysene was 50% degraded after 5 days incubation and 97.5% degraded after 35 days . The protein content of cultures reached a maximum value of 11.5 mugml(-1) aqueous phase, corresponding to 92 mgg(-1) chrysene . (14)C-labelled chrysene was 50% mineralized after 6-8 weeks incubation, 10.7% of the radioactivity was incorporated into cell biomass and 8.4% was found in the aqueous culture supernatant . Sphingomonas sp . CHY-1 also grew on naphthalene, phenanthrene and anthracene, and naphthalene was the preferred substrate, with a doubling time of 6.9 h. FEMS Microbiol Lett, 2004 Dec 15, 241(2), 135 - 41 Quorum-sensing control in Staphylococci - a target for antimicrobial drug therapy? Otto M. Today, we find ourselves in an urgent need for novel antibacterial drugs, as many important human pathogens have acquired multiple antibiotic resistance factors . Among those, Staphylococcus aureus and S . epidermidis play a major role as the leading sources of nosocomial infections . Recently, it has been suggested to develop therapeutics that attack bacterial virulence rather than kill bacteria . Such drugs are called "antipathogenic" and are believed to reduce the development of antibiotic resistance . Specifically, cell-density-dependent gene regulation (quorum-sensing) in bacteria has been proposed as a potential target . While promising reports exist about quorum-sensing blockers in gram-negative bacteria, the use of the staphylococcal quorum-sensing system as a drug target is now seen in an increasingly critical way . Inhibition of quorum-sensing in Staphylococcus has been shown to enhance biofilm formation . Furthermore, down-regulation or mutation of the Staphylococcus quorum-sensing system increases bacterial persistence in device-related infection, suggesting that interference with quorum-sensing would enhance rather than suppress this important type of staphylococcal disease . The chemical nature and biological function of another proposed staphylococcal quorum-sensing inhibitor, named "RIP", are insufficiently characterized . Targeting quorum-sensing systems might in principle constitute a reasonable way to find novel antibacterial drugs . However, as outlined here, this approach requires careful investigation in every specific pathogen and type of infection. Arch Oral Biol, 2005 Jan, 50(1), 23 - 32 Coaggregation profiles of the microflora from root surface caries lesions; Shen S et al.; Bacterial coaggregation reactions between different species and the auto aggregation of the same species are associated with the initiation and development of dental plaque and biofilms . As no such data is available on isolates from root caries lesions, we evaluated, by a visual, semi-quantitative scoring system and a spectrophotometric, quantitative assay, the coaggregation of 22 different wild-type microbial species comprising ten bacterial genera and a single Candida spp . The quantitative coaggregation assay we used proved to be a more sensitive method than the semi-quantitative, visual evaluation as the results yielded the percent coaggregation . Fusobacterium nucleatum, Lactobacillus acidophilus, Streptococcus bovis II/2 and Gemella morbillorum were observed having higher degrees of autoaggregation than the other examined strains . Significant levels of inter-species coaggregation was seen between: (1) Actinomyces spp . and Veillonella spp.; (2) Actinomyces israelii and Peptostreptococcus prevotii; (3) Campylobacter gracilis and Actinomyces spp.; (4) Prevotella intermedia and nine different species; and (5) Fusobacterium nucleatum and six other species . The single Candida albicans isolate did not coaggregate to a significant extent with any of the 21 bacterial isolates studied . Scanning electron microscopy observation of the coaggregation interactions between bacterial pairs having strong coaggregation reactions revealed varying adhesive patterns . Our findings on coaggregation amongst these isolates imply existence of multiple interactions between the coaggregation-inducing bacterial species in root caries . In particular, Actinomyces spp., Veillonella spp., Prevotella spp . and Fusobacterium spp . appear to play a significant role in this context. Am J Orthod Dentofacial Orthop, 2004 Dec, 126(6), 725 - 8 Structural conformation and leaching from in vitro aged and retrieved Invisalign appliances; Schuster S et al.; The objectives of this study were to investigate the structure of Invisalign appliances (Align Technology, Santa Clara, Calif) after intraoral exposure, and to qualitatively and quantitatively characterize the substances leached from the aligners after accelerated in vitro aging . Samples of Invisalign appliances were randomly selected from 10 patients before intraoral placement and after retrieval, and the prepared specimens were subjected to (1) bright-field optical reflection microscopy to study the surface morphology; (2) Fourier transform infrared microspectroscopy to characterize the in vivo changes in molecular composition induced on appliance surfaces, (3) scanning electron microscopy and energy dispersive X-ray microanalysis to identify the elemental composition of integuments formed on the surface, and (4) Vickers hardness (HV 200) testing . Another set of reference and retrieved appliances was subjected to artificial aging for 2 weeks, and the extracts were subjected to gas chromatography-mass spectroscopy . The retrieved appliances demonstrated substantial morphological variation relative to the as-received specimens involving abrasion at the cusp tips, adsorption of integuments, and localized calcification of the precipitated biofilm at stagnation sites . Buccal segments of retrieved appliances showed an increase in hardness, which might be attributed to mastication-induced cold work; however, the clinical implication of this effect on mechanotherapy is unknown . In vitro aged and retrieved appliances were found to leach no traceable amount of substances in an ethanol aging solution. J Urol, 2005 Jan, 173(1), 262 - 6 Does the valve regulated release of urine from the bladder decrease encrustation and blockage of indwelling catheters by crystalline proteus mirabilis biofilms? Sabbuba NA, Stickler DJ, Long MJ, Dong Z, Short TD, Feneley RJ. PURPOSE: We tested whether valve regulated, intermittent flow of urine from catheterized bladders decreases catheter encrustation . MATERIALS AND METHODS: Laboratory models of the catheterized bladder were infected with Proteus mirabilis . Urine was allowed to drain continuously through the catheters or regulated by valves to drain intermittently at predetermined intervals . The time that catheters required to become blocked was recorded and encrustation was visualized by scanning electron microscopy . RESULTS: When a manual valve was used to drain urine from the bladder at 2-hour intervals 4 times during the day, catheters required significantly longer to become blocked than those on continuous drainage (mean 62.6 vs 35.9 hours, p = 0.039) . A similar 1.7-fold increase occurred when urine was drained at 4-hour intervals 3 times daily . Experiments with an automatic valve in which urine was released at 2 or 4-hour intervals through the day and night also showed a significant increase in mean time to blockage compared with continuous drainage (p = 0.001) . Scanning electron microscopy confirmed that crystalline biofilm was less extensive on valve regulated catheters . CONCLUSIONS: Valve regulated, intermittent flow of urine through catheters increases the time that catheters require to become blocked with crystalline biofilm . The most beneficial effect was recorded when urine was released from the bladder at 4-hour intervals throughout the day and nig