Primary Colonizing Betaproteobacteriales Play a Key Role in the Growth of Legionella pneumophila in Biofilms on Surfaces Exposed to Drinking Water Treated by Slow Sand Filtration.

Slow sand filtration with extensive pretreatment reduces the microbial growth potential of drinking water to a minimum level at four surface water supplies in The Netherlands. The potential of these slow sand filtrates (SSFs) to promote microbial growth in warm tap water installations was assessed by measuring biofilm formation and growth of Legionella bacteria on glass and chlorinated polyvinylchloride (CPVC) surfaces exposed to SSFs at 37 ± 2°C in a model system for up to six months. The steady-state biofilm concentration ranged from 230 to 3,980 pg ATP cm-2 on glass and 1.4 (±0.3)-times-higher levels on CPVC. These concentrations correlated significantly with the assimilable organic carbon (AOC) concentrations of the warm water (8 to 24 µg acetate-C equivalents [ac-C eq] liter-1), which were raised about 2 times by mixing cold and heated (70°C) SSFs. All biofilms supported growth of Legionella pneumophila with maximum concentrations ranging from 6 × 102 to 1.5 × 105 CFU cm-2 Biofilms after ≤50 days of exposure were predominated by Betaproteobacteriales, mainly Piscinibacter, Caldimonas, Methyloversatilis, and an uncultured Rhodocyclaceae bacterium. These rapidly growing primary colonizers most likely served as prey for the host amoebae of L. pneumophilaAlphaproteobacteria, mostly Xanthobacteraceae, e.g., Bradyrhizobium, Pseudorhodoplanes, and other amoeba-resistant bacteria, accounted for 37.5% of the clones retrieved. A conceptual model based on a quadratic relationship between the L. pneumophila colony count and the biofilm concentration under steady-state conditions is used to explain the variations in the Legionella CFU pg-1 ATP ratios in the biofilms.IMPORTANCE Proliferation of L. pneumophila in premise plumbing poses a public health threat. Extended water treatment using physicochemical and biofiltration processes, including slow sand filtration, at four surface water supplies in The Netherlands reduces the microbial growth potential of the treated water to a minimum level, and the distributed drinking water complies with high quality standards. However, heating of the water in warm tap water installations increases the concentration of easily assimilable organic compounds, thereby promoting biofilm formation and growth of L. pneumophila Prevention of biofilm formation in plumbing systems by maintenance of a disinfectant residual during distribution and/or further natural organic matter (NOM) removal is not feasible in the supplies studied. Temperature management in combination with optimized hydraulics and material selection are therefore essential to prevent growth of L. pneumophila in premise plumbing systems. Still, reducing the concentration of biodegradable compounds in drinking water by appropriate water treatment is important for limiting the Legionella growth potential.

The role of iron-oxidizing bacteria in biocorrosion: a review.

Lithotrophic iron-oxidizing bacteria depend on reduced iron, Fe(II), as their primary energy source, making them natural candidates for growing in association with steel infrastructure and potentially contributing to microbially influenced corrosion (MIC). This review summarizes recent work on the role of iron-oxidizing bacteria (FeOB) in MIC. By virtue of producing complex 3-dimensional biofilms that result from the accumulation of iron-oxides, FeOB may aid in the colonization of steel surfaces by other microbes involved in MIC. Evidence points to a successional pattern occurring whereby FeOB are early colonizers of mild steel (MS), followed by sulfate-reducing bacteria and other microbes, although studies of aged corrosion products indicate that FeOB do establish a long-term presence. There is evidence that only specific clades of FeOB, with unique adaptations for growing on steel surfaces are part of the MIC community. These are discussed in the context of the larger MIC microbiome.

Biofouling of reverse osmosis membranes: effects of cleaning on biofilm microbial communities, membrane performance, and adherence of extracellular polymeric substances.

Laboratory-scale reverse osmosis (RO) flat-sheet systems were used with two parallel flow cells, one treated with cleaning agents and a control (ie undisturbed). The cleaning efforts increased the affinity of extracellular polymeric substances (EPS) to the RO membrane and altered the biofilm surface structure. Analysis of the membrane biofilm community composition revealed the dominance of Proteobacteria. However, within the phylum Proteobacteria, γ-Proteobacteria dominated the cleaned membrane biofilm, while ß-Proteobacteria dominated the control biofilm. The composition of the fungal phyla was also altered by cleaning, with enhancement of Ascomycota and suppression of Basidiomycota. The results suggest that repeated cleaning cycles select for microbial groups that strongly attach to the RO membrane surface by producing rigid and adhesive EPS that hampers membrane performance.

Peeking under the Iron Curtain: Development of a Microcosm for Imaging the Colonization of Steel Surfaces by Mariprofundus sp. Strain DIS-1, an Oxygen-Tolerant Fe-Oxidizing Bacterium.

Microbially influenced corrosion (MIC) is a major cause of damage to steel infrastructure in the marine environment. Despite their ability to grow directly on Fe(II) released from steel, comparatively little is known about the role played by neutrophilic iron-oxidizing bacteria (FeOB). Recent work has shown that FeOB grow readily on mild steel (1018 MS) incubated in situ or as a substrate for pure cultures in vitro; however, details of how they colonize steel surfaces are unknown yet are important for understanding their effects. In this study, we combine a novel continuously upwelling microcosm with confocal laser scanning microscopy (CLSM) to determine the degree of colonization of 1018 MS by the marine FeOB strain DIS-1. 1018 MS coupons were incubated with sterile seawater (pH 8) inoculated with strain DIS-1. Incubations were performed both under oxic conditions and in an anoxic-to-oxic gradient. Following incubations of 1 to 10 days, the slides were removed from the microcosms and stained to visualize both cells and stalk structures. Stained coupons were visualized by CLSM after being mounted in a custom frame to preserve the three-dimensional structure of the biofilm. The incubation of 1018 MS coupons with strain DIS-1 under oxic conditions resulted in initial attachment of cells within 2 days and nearly total coverage of the coupon with an ochre film within 5 days. CLSM imaging revealed a nonadherent biofilm composed primarily of the Fe-oxide stalks characteristic of strain DIS-1. When incubated with elevated concentrations of Fe(II), DIS-1 colonization of 1018 MS was inhibited. IMPORTANCE: These experiments describe the growth of a marine FeOB in a continuous culture system and represent direct visualizations of steel colonization by FeOB. We anticipate that these experiments will lay the groundwork for studying the mechanisms by which FeOB colonize steel and help to elucidate the role played by marine FeOB in MIC. These observations of the interaction between an FeOB, strain DIS-1, and steel suggest that this experimental system will provide a useful model for studying the interactions between microbes and solid substrates.

Molecular techniques revealed highly diverse microbial communities in natural marine biofilms on polystyrene dishes for invertebrate larval settlement.

Biofilm microbial communities play an important role in the larval settlement response of marine invertebrates. However, the underlying mechanism has yet to be resolved, mainly because of the uncertainties in characterizing members in the communities using traditional 16S rRNA gene-based molecular methods and in identifying the chemical signals involved. In this study, pyrosequencing was used to characterize the bacterial communities in intertidal and subtidal marine biofilms developed during two seasons. We revealed highly diverse biofilm bacterial communities that varied with season and tidal level. Over 3,000 operational taxonomic units with estimates of up to 8,000 species were recovered in a biofilm sample, which is by far the highest number recorded in subtropical marine biofilms. Nineteen phyla were found, of which Cyanobacteria and Proteobacteria were the most dominant one in the intertidal and subtidal biofilms, respectively. Apart from these, Actinobacteria, Bacteroidetes, and Planctomycetes were the major groups recovered in both intertidal and subtidal biofilms, although their relative abundance varied among samples. Full-length 16S rRNA gene clone libraries were constructed for the four biofilm samples and showed similar bacterial compositions at the phylum level to those revealed by pyrosequencing. Laboratory assays confirmed that cyrids of the barnacle Balanus amphitrite preferred to settle on the intertidal rather than subtidal biofilms. This preference was independent of the biofilm bacterial density or biomass but was probably related to the biofilm community structure, particularly, the Proteobacterial and Cyanobacterial groups.

Effects of dietary fiber on the feline gastrointestinal metagenome.

Four healthy adult cats were used in a crossover design to determine phylogeny and metabolic functional capacity of the cat's gastrointestinal microbiota using a metagenomic approach. Healthy adult cats (1.7 years old) were fed diets containing 4% cellulose, fructooligosaccharides (FOS), or pectin for 30 d, at which time fresh fecal samples were collected. Fecal DNA samples from each cat consuming each diet were subjected to 454 pyrosequencing. Dominant phyla determined using two independent databases (MG-RAST and IMG/M) included Firmicutes (mean=36.3 and 49.8%, respectively), Bacteroidetes (mean=36.1 and 24.1%, respectively), and Proteobacteria (mean=12.4 and 11.1%, respectively). Primary functional categories as determined by KEGG were associated with carbohydrates, clustering-based subsystems, protein metabolism, and amino acids and derivatives. Primary functional categories as determined by COG were associated with amino acid metabolism and transport, general function prediction only, and carbohydrate transport and metabolism. Analysis of carbohydrate-active enzymes revealed modifications in several glycoside hydrolases, glycosyl transferases, and carbohydrate-binding molecules with FOS and pectin consumption. While the cat is an obligate carnivore, its gut microbiome is similar regarding microbial phylogeny and gene content to omnivores.

Living in a bottle: Bacteria from sediment-associated Mediterranean waste and potential growth on polyethylene terephthalate.

Ocean pollution is a worldwide environmental challenge that could be partially tackled through microbial applications. To shed light on the diversity and applications of the bacterial communities that inhabit the sediments trapped in artificial containers, we analyzed residues (polyethylene terephthalate [PET] bottles and aluminum cans) collected from the Mediterranean Sea by scanning electron microscopy and next generation sequencing. Moreover, we set a collection of culturable bacteria from the plastisphere that were screened for their ability to use PET as a carbon source. Our results reveal that Proteobacteria are the predominant phylum in all the samples and that Rhodobacteraceae, Woeseia, Actinomarinales, or Vibrio are also abundant in these residues. Moreover, we identified marine isolates with enhanced growth in the presence of PET: Aquimarina intermedia, Citricoccus spp., and Micrococcus spp. Our results suggest that the marine environment is a source of biotechnologically promising bacterial isolates that may use PET or PET additives as carbon sources.

The structural basis for high-affinity uptake of lignin-derived aromatic compounds by proteobacterial TRAP transporters.

The organic polymer lignin is a component of plant cell walls, which like (hemi)-cellulose is highly abundant in nature and relatively resistant to degradation. However, extracellular enzymes released by natural microbial consortia can cleave the ß-aryl ether linkages in lignin, releasing monoaromatic phenylpropanoids that can be further catabolised by diverse species of bacteria. Biodegradation of lignin is therefore important in global carbon cycling, and its natural abundance also makes it an attractive biotechnological feedstock for the industrial production of commodity chemicals. Whilst the pathways for degradation of lignin-derived aromatics have been extensively characterised, much less is understood about how they are recognised and taken up from the environment. The purple phototrophic bacterium Rhodopseudomonas palustris can grow on a range of phenylpropanoid monomers and is a model organism for studying their uptake and breakdown. R. palustris encodes a tripartite ATP-independent periplasmic (TRAP) transporter (TarPQM) linked to genes encoding phenylpropanoid-degrading enzymes. The periplasmic solute-binding protein component of this transporter, TarP, has previously been shown to bind aromatic substrates. Here, we determine the high-resolution crystal structure of TarP from R. palustris as well as the structures of homologous proteins from the salt marsh bacterium Sagittula stellata and the halophile Chromohalobacter salexigens, which also grow on lignin-derived aromatics. In combination with tryptophan fluorescence ligand-binding assays, our ligand-bound co-crystal structures reveal the molecular basis for high-affinity recognition of phenylpropanoids by these TRAP transporters, which have potential for improving uptake of these compounds for biotechnological transformations of lignin.

Neutrophilic iron-oxidizing "zetaproteobacteria" and mild steel corrosion in nearshore marine environments.

Microbiologically influenced corrosion (MIC) of mild steel in seawater is an expensive and enduring problem. Little attention has been paid to the role of neutrophilic, lithotrophic, iron-oxidizing bacteria (FeOB) in MIC. The goal of this study was to determine if marine FeOB related to Mariprofundus are involved in this process. To examine this, field incubations and laboratory microcosm experiments were conducted. Mild steel samples incubated in nearshore environments were colonized by marine FeOB, as evidenced by the presence of helical iron-encrusted stalks diagnostic of the FeOB Mariprofundus ferrooxydans, a member of the candidate class "Zetaproteobacteria." Furthermore, Mariprofundus-like cells were enriched from MIC biofilms. The presence of Zetaproteobacteria was confirmed using a Zetaproteobacteria-specific small-subunit (SSU) rRNA gene primer set to amplify sequences related to M. ferrooxydans from both enrichments and in situ samples of MIC biofilms. Temporal in situ incubation studies showed a qualitative increase in stalk distribution on mild steel, suggesting progressive colonization by stalk-forming FeOB. We also isolated a novel FeOB, designated Mariprofundus sp. strain GSB2, from an iron oxide mat in a salt marsh. Strain GSB2 enhanced uniform corrosion from mild steel in laboratory microcosm experiments conducted over 4 days. Iron concentrations (including precipitates) in the medium were used as a measure of corrosion. The corrosion in biotic samples (7.4 ± 0.1 mM) was significantly higher than that in abiotic controls (5.0 ± 0.1 mM). These results have important implications for the role of FeOB in corrosion of steel in nearshore and estuarine environments. In addition, this work shows that the global distribution of Zetaproteobacteria is far greater than previously thought.

Facultative methylotrophs from the human oral cavity and methylotrophy in strains of Gordonia, Leifsonia, and Microbacterium.

We show that bacteria with methylotrophic potential are ubiquitous in the human mouth microbiota. Numerous strains of Actinobacteria (Brevibacterium, Gordonia, Leifsonia, Microbacterium, Micrococcus, Rhodococcus) and Proteobacteria (Achromobacter, Klebsiella, Methylobacterium, Pseudomonas, Ralstonia) were isolated, and one strain of each of the eleven genera was studied in detail. These strains expressed enzymes associated with methylotrophic metabolism (methanol, methylamine, and formate dehydrogenases), and the assimilation of one-carbon compounds by the serine pathway (hydroxypyruvate reductase). Methylotrophic growth of the strains was enhanced by the addition of glass beads to cultures, suggesting that they may naturally occur in biofilms in the mouth. This is the first report of Gordonia, Leifsonia, and Rhodococcus being present in the mouth and of the unequivocal demonstration for the first time of the methylotrophic potential of strains of Gordonia, Leifsonia, and Microbacterium.

Increased bioclogging and corrosion risk by sulfate addition during iodine recovery at a natural gas production plant.

Iodine recovery at a natural gas production plant in Japan involved the addition of sulfuric acid for pH adjustment, resulting in an additional about 200 mg/L of sulfate in the waste brine after iodine recovery. Bioclogging occurred at the waste brine injection well, causing a decrease in well injectivity. To examine the factors that contribute to bioclogging, an on-site experiment was conducted by amending 10 L of brine with different conditions and then incubating the brine for 5 months under open air. The control case was exposed to open air but did not receive additional chemicals. When sulfate addition was coupled with low iodine, there was a drastic increase in the total amount of accumulated biomass (and subsequently the risk of bioclogging) that was nearly six times higher than the control. The bioclogging-associated corrosion rate of carbon steel was 84.5 µm/year, which is four times higher than that observed under other conditions. Analysis of the microbial communities by denaturing gradient gel electrophoresis revealed that the additional sulfate established a sulfur cycle and induced the growth of phototrophic bacteria, including cyanobacteria and purple bacteria. In the presence of sulfate and low iodine levels, cyanobacteria and purple bacteria bloomed, and the accumulation of abundant biomass may have created a more conducive environment for anaerobic sulfate-reducing bacteria. It is believed that the higher corrosion rate was caused by a differential aeration cell that was established by the heterogeneous distribution of the biomass that covered the surface of the test coupons.

Evaluation of biocathodes in freshwater and brackish sediment microbial fuel cells.

Biofilms on biocathodes can catalyze the cathodic oxygen reduction and accordingly guarantee high cathode redox potentials. The present research assessed the use of biocathodes in full-sediment microbial fuel cells. Carbon felt-based biocathodes were evaluated in freshwater systems, and an extension of their application to brackish systems and/or stainless steel webs as base material was considered. Efficient biocathodes could be developed within days through inoculation with active microorganisms. Carbon felt was found most suited for the biocathodes in freshwater with increased performance at salinities around 80-250 mM. Maximum long-term performance reached 12.3 microW cm(-2) cathode. The relative benefit of stainless steel seemed to increase with increasing salinity. A combination of stainless steel cathodes with biofilms could, however, also result in decreased electrical performance. In an efficiently catalyzing cathodic biofilm, an enrichment with an uncultured Proteobacterium--previously correlated with steel waste--was observed.

High-rate anaerobic decolorization of methyl orange from synthetic azo dye wastewater in a methane-based hollow fiber membrane bioreactor.

Anaerobic biological techniques are widely used in the reductive decolorization of textile wastewater. However, the decolorization efficiency of textile wastewater by conventional anaerobic biological techniques is generally limited due to the low biomass retention capacity and short hydraulic retention time (HRT). In this study, a methane-based hollow fiber membrane bioreactor (HfMBR) was initially inoculated with an enriched anaerobic methane oxidation (AOM) culture to rapidly form an anaerobic biofilm. Then, synthetic azo dye wastewater containing methyl orange (MO) was fed into the HfMBR. MO decolorization efficiency of ∼ 100 % (HRT = 2 to 1.5 days) and maximum decolorization rate of 883 mg/L/day (HRT = 0.5 day) were obtained by the stepwise increase of the MO loading rate into the methane-based HfMBR. Scanning electron microscopy (SEM) and fluorescence in situ hybridization (FISH) analysis visually revealed that archaea clusters formed synergistic consortia with adjacent bacteria. Quantitative PCR (qPCR), phylogenetic and high-throughput sequencing analysis results further confirmed the biological consortia formation of methane-related archaea and partner bacteria, which played a synergistic role in MO decolorization. The high removal efficiency and stable microbial structure in HfMBR suggest it is a potentially effective technique for high-toxic azo dyes removal from textile wastewater.

Diarrhoeal events can trigger long-term Clostridium difficile colonization with recurrent blooms.

Although Clostridium difficile is widely considered an antibiotic- and hospital-associated pathogen, recent evidence indicates that this is an insufficient depiction of the risks and reservoirs. A common thread that links all major risk factors of infection is their association with gastrointestinal disturbances, but this relationship to C. difficile colonization has never been tested directly. Here, we show that disturbances caused by diarrhoeal events trigger susceptibility to C. difficile colonization. Using survey data of the human gut microbiome, we detected C. difficile colonization and blooms in people recovering from food poisoning and Vibrio cholerae infections. Carriers remained colonized for year-long time scales and experienced highly variable patterns of C. difficile abundance, where increased shedding over short periods of 1-2 d interrupted week-long periods in which C. difficile was undetectable. Given that short shedding events were often linked to gastrointestinal disturbances, our results help explain why C. difficile is frequently detected as a co-infecting pathogen in patients with diarrhoea. To directly test the impact of diarrhoea on susceptibility to colonization, we developed a mouse model of variable disturbance intensity, which allowed us to monitor colonization in the absence of disease. As mice exposed to avirulent C. difficile spores ingested increasing quantities of laxatives, more individuals experienced C. difficile blooms. Our results indicate that the likelihood of colonization is highest in the days immediately following acute disturbances, suggesting that this could be an important window during which transmission could be interrupted and the incidence of infection lowered.

Stability of partial nitrification and microbial population dynamics in a bioaugmented membrane bioreactor.

Bioaugmentation of bioreactors focuses on the removal of numerous organics, with little attention typically paid to the maintenance of high and stable nitrite accumulation in partial nitrification. In this study, a bioaugmented membrane bioreactor (MBR) inoculated with enriched ammonia-oxidizing bacteria (AOB) was developed, and the effects of dissolved oxygen (DO) and temperature on stability of partial nitrification and microbial community structure, in particular on nitrifying community were evaluated. The results showed that DO and temperature played the most important roles in the stability of partial nitrification in the bioaugmented MBR. The optimal operation conditions were found at 2-3 mgDO/L and 30 degrees C, achieving 95% ammonia oxidization efficiency and 0.95 of nitrite ratio (NO2-/NOx-). High-DO (5-6 mg/L) and low-temperature (20 degrees C) had negative impacts on nitrite accumulation, leading to its drop to 0.6. However, the nitrite ratio achieved in the bioaugmented MBR was higher than that in most previous literatures. Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH) were used to provide an insight into the microbial community. It showed that Nitrosomonas-like species as the only detected AOB remained predominant in the bioaugmented MBR all the time, which coexisted with numerous heterotrophic bacteria. The heterotrophic bacteria responsible for mineralizing soluble microbial products (SMP) produced by nitrifiers belonged to Cytophaga-Flavobacterium-Bacteroides (CFB) group, alpha-, beta-, and gamma- Proteobacteria. The fraction of AOB ranging from 77% to 54% was much higher than that of NOB (0.4-0.9%), which might be the primary cause for the high and stable nitrite accumulation in the bioaugmented MBR.

Microbial biofilm formation and community structure on low-density polyethylene microparticles in lake water microcosms.

The occurrence of microplastics (MPs) in the environment has been gaining widespread attention globally. MP-colonizing microorganisms are important links for MPs contamination in various ecosystems, but have not been well understood. To partially address this issue, the present study investigated biofilm formation by microorganisms originating from lake water on low-density polyethylene (LDPE) MPs using a cultivation approach and the surface-related effects on the MP-associated microbial communities using 16S rRNA high-throughput sequencing. With the addition of nonionic surfactants and UV-irradiation pretreatment that changed the surface properties of LDPE MPs, more microorganisms were colonized on LDPE surface. Microbial community analysis indicated that LDPE MPs were primarily colonized by the phyla Proteobacteria, Bacteroidetes and Firmicutes, and the surface roughness and hydrophobicity of MP were important factors shaping the LDPE MP-associated microbial community structure. Half of the top 20 most abundant genera colonizing on LDPE were found to be potential pathogens, e.g., plant pathogens Agrobacterium, nosocomial pathogens Chryseobacterium and fish pathogens Flavobacterium. This study demonstrated rapid bacterial colonization of LDPE MPs in lake water microcosms, the role of MPs as transfer vectors for harmful microorganisms in lake water, and provided a first glimpse into the effect of surface properties on LDPE MP-associated biofilm communities.

Diversity and distribution of ecotypes of the aerobic anoxygenic phototrophy gene pufM in the Delaware estuary.

The diversity of aerobic anoxygenic phototrophic (AAP) bacteria has been examined in marine habitats, but the types of AAP bacteria in estuarine waters and distribution of ecotypes in any environment are not well known. The goal of this study was to determine the diversity of AAP bacteria in the Delaware estuary and to examine the distribution of select ecotypes using quantitative PCR (qPCR) assays for the pufM gene, which encodes a protein in the light reaction center of AAP bacteria. In PCR libraries from the Delaware River, pufM genes similar to those from Beta- (Rhodoferax-like) or Gammaproteobacteria comprised at least 50% of the clones, but the expressed pufM genes from the river were not dominated by these two groups in August 2002 (less than 31% of clones). In four transects, qPCR data indicated that the gammaproteobacterial type of pufM was abundant only near the mouth of the bay whereas Rhodoferax-like AAP bacteria were restricted to waters with a salinity of <5. In contrast, a Rhodobacter-like pufM gene was ubiquitous, but its distribution along the salinity gradient varied with the season. High fractions (12 to 24%) of all three pufM types were associated with particles. The data suggest that different groups of AAP bacteria are controlled by different environmental factors, which may explain current difficulties in predicting the distribution of total AAP bacteria in aquatic environments.

A novel approach for bioremediation of a coastal marine wastewater effluent based on artificial microbial mats.

A novel alternative for wastewater effluent bioremediation was developed using constructed microbial mats on low-density polyester. This biotechnology showed high removal efficiencies for nitrogen and phosphorous in a short retention time (48 h): 94% for orthophosphate (7.78 g PO(3-)(4) - P m(3) d(-1)), 79% for ammonium (11.30 g NH(4)(+) - N m(-3) d(-1)), 78% for nitrite (7.46 g NO(2)(-) m(-3) d(-1)), and 83% for nitrate (8.55 g NO(3)(-) N m(-3) d(-1)). The microbial mats were dominated by Cyanobacteria genera such as Chroococcus sp., Lyngbya sp., and bacteria of the subclass Proteobacteria representative of the Eubacteria Domain. Nitzschia sp. was the dominant Eukaryote Domain. Various N and P substrates in the wastewater permit the growth of self-forming and self-sustaining bacterial, microalgal, and cyanobacterial communities on a polyester support. The result is the continuous, self-sufficient growth of microbial mats. This is an innovative, economical, and environmentally safe alternative for the treatment of wastewater effluents in coastal marine environments.

Household triclosan and triclocarban effects on the infant and maternal microbiome.

In 2016, the US Food and Drug Administration banned the use of specific microbicides in some household and personal wash products due to concerns that these chemicals might induce antibiotic resistance or disrupt human microbial communities. Triclosan and triclocarban (referred to as TCs) are the most common antimicrobials in household and personal care products, but the extent to which TC exposure perturbs microbial communities in humans, particularly during infant development, was unknown. We conducted a randomized intervention of TC-containing household and personal care products during the first year following birth to characterize whether TC exposure from wash products perturbs microbial communities in mothers and their infants. Longitudinal survey of the gut microbiota using 16S ribosomal RNA amplicon sequencing showed that TC exposure from wash products did not induce global reconstruction or loss of microbial diversity of either infant or maternal gut microbiotas. Broadly antibiotic-resistant species from the phylum Proteobacteria, however, were enriched in stool samples from mothers in TC households after the introduction of triclosan-containing toothpaste. When compared by urinary triclosan level, agnostic to treatment arm, infants with higher triclosan levels also showed an enrichment of Proteobacteria species. Despite the minimal effects of TC exposure from wash products on the gut microbial community of infants and adults, detected taxonomic differences highlight the need for consumer safety testing of antimicrobial self-care products on the human microbiome and on antibiotic resistance.

Dietary Fiber Intake Regulates Intestinal Microflora and Inhibits Ovalbumin-Induced Allergic Airway Inflammation in a Mouse Model.

BACKGROUND: Recently, academic studies suggest that global growth of airway allergic disease has a close association with dietary changes including reduced consumption of fiber. Therefore, appropriate dietary fiber supplementation might be potential to prevent airway allergic disease (AAD). OBJECTIVE: We investigated whether dietary fiber intake suppressed the induction of AAD and tried to elucidate the possible underlying mechanisms. METHODS: The control mice and AAD model mice fed with 4% standard-fiber chow, while low-fiber group of mice fed with a 1.75% low-fiber chow. The two fiber-intervened groups including mice, apart from a standard-fiber diet, were also intragastric (i.g.) administrated daily with poorly fermentable cellulose or readily fermentable pectin (0.4% of daily body weight), respectively. All animals except normal mice were sensitized and challenged with ovalbumin (OVA) to induce airway allergic inflammation. Hallmarks of AAD were examined by histological analysis and ELISA. The variation in intestinal bacterial composition was assessed by qualitative analysis of 16S ribosomal DNA (rDNA) content in fecal samples using real-time PCR. RESULTS: Low-fiber diet aggravated inflammatory response in ovalbumin-induced allergic mice, whereas dietary fiber intake significantly suppressed the allergic responses, attenuated allergic symptoms of nasal rubbing and sneezing, decreased the pathology of eosinophil infiltration and goblet cell metaplasia in the nasal mucosa and lung, inhibited serum OVA-specific IgE levels, and lowered the levels of Th2 cytokines in NALF and BALF, but, increased Th1 (IFN-γ) cytokines. Additionally, dietary fiber intake also increased the proportion of Bacteroidetes and Actinobacteria, and decreased Firmicutes and Proteobacteria. Levels of probiotic bacteria, such as Lactobacillus and Bifidobacterium, were upgraded significantly. CONCLUSION: Long-term deficiency of dietary fiber intake increases the susceptibility to AAD, whereas proper fiber supplementation promotes effectively the balance of Th1/Th2 immunity and then attenuates allergic inflammatory responses significantly, as well as optimizes the structure of intestinal microbiota, which suggests potential for novel preventive and therapeutic intervention.