scholarly journals Regulation of Biofilm Aging and Dispersal inBacillus subtilisby the Alternative Sigma Factor SigB

2018 ◽  
Vol 201 (2) ◽  
Author(s):  
M. Bartolini ◽  
S. Cogliati ◽  
D. Vileta ◽  
C. Bauman ◽  
L. Rateni ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Bacterial Survival ◽  
Medical Systems ◽  
Biofilm Growth ◽  
Waste Products ◽  
Content Type ◽  
Regulatory Cascade ◽  
Regulatory Circuit ◽  
Metabolic Conditions ◽  
Biofilm Development

ABSTRACTBacterial biofilms are important in natural settings, biotechnology, and medicine. However, regulation of biofilm development and its persistence in different niches is complex and only partially understood. One key step during the biofilm life cycle is dispersal, when motile cells abandon the mature biofilm to spread out and colonize new niches. Here, we show that in the model bacteriumBacillus subtilisthe general stress transcription factor SigB is essential for halting detrimental overgrowth of mature biofilm and for triggering dispersal when nutrients become limited. Specifically, SigB-deficient biofilms were larger than wild-type biofilms but exhibited accelerated cell death, significantly greater sensitivity to different stresses, and reduced dispersal. Interestingly, the signal detected by SigB to limit biofilm growth was transduced through the RsbP-dependent metabolic arm of the SigB regulatory cascade, which in turn positively controlled expression of SinR, the master regulator of biofilm formation and cell motility. This novel SigB-SinR regulatory circuit might be important in controlling the fitness of biofilms (either beneficial or harmful) in diverse environments.IMPORTANCEBiofilms are crucial for bacterial survival, adaptation, and dissemination in natural, industrial, and medical systems. Sessile cells embedded in the self-produced extracellular matrix of the biofilm benefit from a division of labor and are protected from environmental insults. However, as the biofilm ages, cells become stressed because of overcrowding, starvation, and accumulation of waste products. How does the sessile biofilm community sense and respond to stressful conditions? Here, we show that inBacillus subtilis, the transcription factors SigB and SinR control whether cells remain in or leave a biofilm when metabolic conditions become unfavorable. This novel SigB-SinR regulatory circuit might be important for controlling the fitness of biofilms (either beneficial or harmful) in diverse environments.

scholarly journals Bacteriophage-Mediated Control of a Two-Species Biofilm Formed by Microorganisms Causing Catheter-Associated Urinary Tract Infections in anIn VitroUrinary Catheter Model

2014 ◽  
Vol 59 (2) ◽  
pp. 1127-1137 ◽  
Author(s):  
Susan M. Lehman ◽  
Rodney M. Donlan
Keyword(s):  
Mixed Species ◽  
Biofilm Inhibition ◽  
Biofilm Growth ◽  
Content Type ◽  
Patient Morbidity ◽  
Phage Cocktail ◽  
Artificial Urine ◽  
Tract Infections ◽  
Biofilm Development

ABSTRACTMicroorganisms from a patient or their environment may colonize indwelling urinary catheters, forming biofilm communities on catheter surfaces and increasing patient morbidity and mortality. This study investigated the effect of pretreating hydrogel-coated silicone catheters with mixtures ofPseudomonas aeruginosaandProteus mirabilisbacteriophages on the development of single- and two-species biofilms in a multiday continuous-flowin vitromodel using artificial urine. Novel phages were purified from sewage, characterized, and screened for their abilities to reduce biofilm development by clinical isolates of their respective hosts. Our screening data showed that artificial urine medium (AUM) is a valid substitute for human urine for the purpose of evaluating uropathogen biofilm control by these bacteriophages. Defined phage cocktails targetingP. aeruginosaandP. mirabiliswere designed based on the biofilm inhibition screens. Hydrogel-coated catheters were pretreated with one or both cocktails and challenged with approximately 1 × 103CFU/ml of the corresponding pathogen(s). The biofilm growth on the catheter surfaces in AUM was monitored over 72 to 96 h. Phage pretreatment reducedP. aeruginosabiofilm counts by 4 log10CFU/cm2(P≤ 0.01) andP. mirabilisbiofilm counts by >2 log10CFU/cm2(P≤ 0.01) over 48 h. The presence ofP. mirabiliswas always associated with an increase in lumen pH from 7.5 to 9.5 and with eventual blockage of the reactor lines. The results of this study suggest that pretreatment of a hydrogel urinary catheter with a phage cocktail can significantly reduce mixed-species biofilm formation by clinically relevant bacteria.

Effects of carbon to nitrogen ratios on amounts and composition of Bacillus subtilis biofilms

2020 ◽  
Author(s):  
Natalia Cortes Osorio ◽  
Robert Endrika ◽  
Karsten Kalbitz ◽  
Cordula Vogel
Keyword(s):  
Bacillus Subtilis ◽  
Extracellular Polymeric Substances ◽  
High Vacuum ◽  
Chemical Properties ◽  
High Ratio ◽  
Natural Environments ◽  
Radial Expansion ◽  
Biofilm Growth ◽  
Microbial Cells ◽  
Biofilm Development

<p>In natural environments, bacteria can be found as multicellular communities exhibiting a high degree of structure, denominated biofilms. Biofilms are composed of microbial cells, often of multiple species, embedded within a matrix of extracellular polymeric substances (EPS). The exact composition, physical and chemical properties, and amounts of these components varies depending on their growth conditions. However, it remains unclear how nutrient availability drives the allocation into cell growth or EPS production, especially under conditions found in soils. Here we aimed to evaluate the effect of various C/N ratios on <em>Bacillus subtilis</em> biofilm growth (spatial expansion and structure) and their EPS composition. We hypothesized that the largest biofilm development and highest EPS production by <em>Bacillus subtilis</em> would be caused by a nutrient imbalance reflected in C/N ratios, especially high C availability. Biofilms were grown on membranes on MSgg agar plates with C/N ratios of 1:1, 10:1, 25:1 and 100:1. Several methods from macroscopic observations over EPS extraction and determination up to various microscopic visualisation techniques were used. The radial expansion of the biofilm was measured, followed by EPS extraction to quantify EPS-proteins and EPS-polysaccharides. Hydrated biofilm samples were studied regarding their biofilm structures by scanning electron microscopy (SEM) within the environmental mode at approximately 97% humidity. Fixed, dehydrated and embedded samples were used to evaluate the biofilm height and internal structure with SEM in high vacuum mode. Low C/N ratio (1:1) resulted in the smallest biofilms in terms of radial expansion and biofilm height, with densely packed layers of cells and low amounts of EPS. Our first results revealed that the highest biofilm productions were observed at C/N ratio of 10:1 and 25:1. The microscopic approaches indicated that biofilms growing at C/N ratios of 100:1 produced the highest amount of EPS. Furthermore, changes in the microscopical features of the biofilms were detected with different structures along the biofilm regions affected by the nutrient conditions. These results suggest that the C/N ratio has a large impact on the biofilm development and structure, with different allocations into microbial cells and EPS. Overall, the results obtained until now allowed us to accept the initial hypothesis, indicating that higher C/N ratios induce a higher EPS production. This suggests that environments containing a high ratio between carbon and the limiting nutrient, often nitrogen, may favour polysaccharide production, probably because energy from the carbon excess is used for polysaccharide biosynthesis.</p>

scholarly journals A Membrane-Embedded Amino Acid Couples the SpoIIQ Channel Protein to Anti-Sigma Factor Transcriptional Repression during Bacillus subtilis Sporulation

2016 ◽  
Vol 198 (9) ◽  
pp. 1451-1463 ◽  
Author(s):  
Kelly A. Flanagan ◽  
Joseph D. Comber ◽  
Elizabeth Mearls ◽  
Colleen Fenton ◽  
Anna F. Wang Erickson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Amino Acid ◽  
Sigma Factor ◽  
Late Gene ◽  
Late Gene Expression ◽  
Gene Encoding ◽  
Content Type ◽  
Regulatory Circuit ◽  
Gene Regulatory

ABSTRACTSpoIIQ is an essential component of a channel connecting the developing forespore to the adjacent mother cell duringBacillus subtilissporulation. This channel is generally required for late gene expression in the forespore, including that directed by the late-acting sigma factor σG. Here, we present evidence that SpoIIQ also participates in a previously unknown gene regulatory circuit that specifically represses expression of the gene encoding the anti-sigma factor CsfB, a potent inhibitor of σG. ThecsfBgene is ordinarily transcribed in the forespore only by the early-acting sigma factor σF. However, in a mutant lacking the highly conserved SpoIIQ transmembrane amino acid Tyr-28,csfBwas also aberrantly transcribed later by σG, the very target of CsfB inhibition. This regulation ofcsfBby SpoIIQ Tyr-28 is specific, given that the expression of other σF-dependent genes was unaffected. Moreover, we identified a conserved element within thecsfBpromoter region that is both necessary and sufficient for SpoIIQ Tyr-28-mediated inhibition. These results indicate that SpoIIQ is a bifunctional protein that not only generally promotes σGactivity in the forespore as a channel component but also specifically maximizes σGactivity as part of a gene regulatory circuit that represses σG-dependent expression of its own inhibitor, CsfB. Finally, we demonstrate that SpoIIQ Tyr-28 is required for the proper localization and stability of the SpoIIE phosphatase, raising the possibility that these two multifunctional proteins cooperate to fine-tune developmental gene expression in the forespore at late times.IMPORTANCECellular development is orchestrated by gene regulatory networks that activate or repress developmental genes at the right time and place. Late gene expression in the developingBacillus subtilisspore is directed by the alternative sigma factor σG. The activity of σGrequires a channel apparatus through which the adjacent mother cell provides substrates that generally support gene expression. Here we report that the channel protein SpoIIQ also specifically maximizes σGactivity as part of a previously unknown regulatory circuit that prevents σGfrom activating transcription of the gene encoding its own inhibitor, the anti-sigma factor CsfB. The discovery of this regulatory circuit significantly expands our understanding of the gene regulatory network controlling late gene expression in the developingB. subtilisspore.

scholarly journals Metabolic Remodeling during Biofilm Development ofBacillus subtilis

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Tippapha Pisithkul ◽  
Jeremy W. Schroeder ◽  
Edna A. Trujillo ◽  
Ponlkrit Yeesin ◽  
David M. Stevenson ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Regulatory Networks ◽  
Developmental Process ◽  
Central Carbon Metabolism ◽  
Bacterial Biofilm ◽  
Biofilm Growth ◽  
Time Resolved ◽  
Content Type ◽  
Metabolic Remodeling ◽  
Biofilm Development

ABSTRACTBiofilms are structured communities of tightly associated cells that constitute the predominant state of bacterial growth in natural and human-made environments. Although the core genetic circuitry that controls biofilm formation in model bacteria such asBacillus subtilishas been well characterized, little is known about the role that metabolism plays in this complex developmental process. Here, we performed a time-resolved analysis of the metabolic changes associated with pellicle biofilm formation and development inB. subtilisby combining metabolomic, transcriptomic, and proteomic analyses. We report surprisingly widespread and dynamic remodeling of metabolism affecting central carbon metabolism, primary biosynthetic pathways, fermentation pathways, and secondary metabolism. Most of these metabolic alterations were hitherto unrecognized as biofilm associated. For example, we observed increased activity of the tricarboxylic acid (TCA) cycle during early biofilm growth, a shift from fatty acid biosynthesis to fatty acid degradation, reorganization of iron metabolism and transport, and a switch from acetate to acetoin fermentation. Close agreement between metabolomic, transcriptomic, and proteomic measurements indicated that remodeling of metabolism during biofilm development was largely controlled at the transcriptional level. Our results also provide insights into the transcription factors and regulatory networks involved in this complex metabolic remodeling. Following upon these results, we demonstrated that acetoin production via acetolactate synthase is essential for robust biofilm growth and has the dual role of conserving redox balance and maintaining extracellular pH. This report represents a comprehensive systems-level investigation of the metabolic remodeling occurring duringB. subtilisbiofilm development that will serve as a useful road map for future studies on biofilm physiology.IMPORTANCEBacterial biofilms are ubiquitous in natural environments and play an important role in many clinical, industrial, and ecological settings. Although much is known about the transcriptional regulatory networks that control biofilm formation in model bacteria such asBacillus subtilis, very little is known about the role of metabolism in this complex developmental process. To address this important knowledge gap, we performed a time-resolved analysis of the metabolic changes associated with bacterial biofilm development inB. subtilisby combining metabolomic, transcriptomic, and proteomic analyses. Here, we report a widespread and dynamic remodeling of metabolism affecting central carbon metabolism, primary biosynthetic pathways, fermentation pathways, and secondary metabolism. This report serves as a unique hypothesis-generating resource for future studies on bacterial biofilm physiology. Outside the biofilm research area, this work should also prove relevant to any investigators interested in microbial physiology and metabolism.

scholarly journals Real-Time Microscopic Observation of Candida Biofilm Development and Effects Due to Micafungin and Fluconazole

2013 ◽  
Vol 57 (5) ◽  
pp. 2226-2230 ◽  
Author(s):  
Yukihiro Kaneko ◽  
Susumu Miyagawa ◽  
On Takeda ◽  
Masateru Hakariya ◽  
Satoru Matsumoto ◽  
...  
Keyword(s):  
Real Time ◽  
Time Lapse ◽  
Time Data ◽  
Biofilm Growth ◽  
Content Type ◽  
Biofilm Thickness ◽  
Ergosterol Synthesis ◽  
Glucan Synthesis ◽  
Biofilm Development ◽  
Observation Period

ABSTRACTTo understand the process ofCandidabiofilm development and the effects of antifungal agents on biofilms, we analyzed real-time data comprising time-lapse images taken at times separated by brief intervals. The growth rate was calculated by measuring the change of biofilm thickness every hour. For the antifungal study, 5-h-old biofilms ofCandida albicanswere treated with either micafungin (MCFG) or fluconazole (FLCZ). MCFG began to suppress biofilm growth a few minutes after the initiation of the treatment, and this effect was maintained over the course of the observation period. In contrast, the suppressive effects of FLCZ on biofilm growth took longer to manifest: biofilms grew in the first 5 h after treatment, and then their growth was suppressed over the next 10 h, finally producing results similar to those observed with MCFG. MCFG was also involved in the disruption of cells in the biofilms, releasing string-like structures (undefined extracellular component) from the burst hyphae. Thus, MCFG inhibited the detachment of yeast cell clusters from the tips of hyphae. In contrast, FLCZ did not disrupt biofilm cells. MCFG also showed fast antifungal activity againstCandida parapsilosisbiofilms. In conclusion, our results show that inhibition of glucan synthesis due to MCFG contributed not only to fungicidal activity but also to the immediate suppression of biofilm growth, while FLCZ suppressed growth by inhibiting ergosterol synthesis. Therefore, those characteristic differences should be considered when treating clinical biofilm infections.

scholarly journals Role of Ribonucleotide Reductase in Bacillus subtilis Stress-Associated Mutagenesis

2016 ◽  
Vol 199 (4) ◽  
Author(s):  
Karla Viridiana Castro-Cerritos ◽  
Ronald E. Yasbin ◽  
Eduardo A. Robleto ◽  
Mario Pedraza-Reyes
Keyword(s):  
Bacillus Subtilis ◽  
Ribonucleotide Reductase ◽  
Single Class ◽  
Content Type ◽  
Conditional Mutant ◽  
Dna Replication And Repair ◽  
Metabolic Conditions ◽  
Study Support ◽  
Encoding Genes

ABSTRACT The Gram-positive microorganism Bacillus subtilis relies on a single class Ib ribonucleotide reductase (RNR) to generate 2′-deoxyribonucleotides (dNDPs) for DNA replication and repair. In this work, we investigated the influence of RNR levels on B. subtilis stationary-phase-associated mutagenesis (SPM). Since RNR is essential in this bacterium, we engineered a conditional mutant of strain B. subtilis YB955 (hisC952 metB5 leu427) in which expression of the nrdEF operon was modulated by isopropyl-β-d-thiogalactopyranoside (IPTG). Moreover, genetic inactivation of ytcG, predicted to encode a repressor (NrdR) of nrdEF in this strain, dramatically increased the expression levels of a transcriptional nrdE-lacZ fusion. The frequencies of mutations conferring amino acid prototrophy in three genes were measured in cultures under conditions that repressed or induced RNR-encoding genes. The results revealed that RNR was necessary for SPM and overexpression of nrdEF promoted growth-dependent mutagenesis and SPM. We also found that nrdEF expression was induced by H2O2 and such induction was dependent on the master regulator PerR. These observations strongly suggest that the metabolic conditions operating in starved B. subtilis cells increase the levels of RNR, which have a direct impact on SPM. IMPORTANCE Results presented in this study support the concept that the adverse metabolic conditions prevailing in nutritionally stressed bacteria activate an oxidative stress response that disturbs ribonucleotide reductase (RNR) levels. Such an alteration of RNR levels promotes mutagenic events that allow Bacillus subtilis to escape from growth-limited conditions.

scholarly journals Role ofepaQ, a Previously UncharacterizedEnterococcus faecalisGene, in Biofilm Development and Antimicrobial Resistance

2019 ◽  
Vol 201 (18) ◽  
Author(s):  
Michelle L. Korir ◽  
Jennifer L. Dale ◽  
Gary M. Dunny
Keyword(s):  
Antibiotic Resistance ◽  
Biofilm Formation ◽  
Cell Surface Hydrophobicity ◽  
Opportunistic Pathogen ◽  
Surface Hydrophobicity ◽  
Biofilm Growth ◽  
Content Type ◽  
Biofilm Architecture ◽  
High Level ◽  
Biofilm Development

ABSTRACTEnterococcus faecalisis a commensal of the human gastrointestinal tract; it is also an opportunistic pathogen and one of the leading causes of hospital-acquired infections.E. faecalisproduces biofilms that are highly resistant to antibiotics, and it has been previously reported that certain genes of theepaoperon contribute to biofilm-associated antibiotic resistance. Despite several studies examining theepaoperon, many gene products of this operon remain annotated as hypothetical proteins. Here, we further explore theepaoperon; we identifiedepaQ, currently annotated as encoding a hypothetical membrane protein, as being important for biofilm formation in the presence of the antibiotic daptomycin. Mutants with disruptions ofepaQwere more susceptible to daptomycin relative to the wild type, suggesting its importance in biofilm-associated antibiotic resistance. Furthermore, the ΔepaQmutant exhibited an altered biofilm architectural arrangement and formed small aggregates in liquid cultures. Our cumulative data show thatepamutations result in altered polysaccharide content, increased cell surface hydrophobicity, and decreased membrane potential. Surprisingly, severalepamutations significantly increased resistance to the antibiotic ceftriaxone, indicating that the way in which theepaoperon impacts antibiotic resistance is antibiotic dependent. These results further define the key role ofepain antibiotic resistance in biofilms and in biofilm architecture.IMPORTANCEE. faecalisis a common cause of nosocomial infection, has a high level of antibiotic resistance, and forms robust biofilms. Biofilm formation is associated with increased antibiotic resistance. Therefore, a thorough understanding of biofilm-associated antibiotic resistance is important for combating resistance. Several genes from theepaoperon have previously been implicated in biofilm-associated antibiotic resistance, pathogenesis, and competitive fitness in the GI tract, but most genes in this locus remain uncharacterized. Here, we examineepaQ,which has not been characterized functionally. We show that the ΔepaQmutant exhibits reduced biofilm formation in the presence of daptomycin, altered biofilm architecture, and increased resistance to ceftriaxone, further expanding our understanding of the contribution of this operon to intrinsic enterococcal antibiotic resistance and biofilm growth.

scholarly journals Adaptation of Mycobacterium tuberculosis to Biofilm Growth Is Genetically Linked to Drug Tolerance

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Jacob P. Richards ◽  
Wenlong Cai ◽  
Nicholas A. Zill ◽  
Wenjun Zhang ◽  
Anil K. Ojha
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Drug Tolerance ◽  
Growth Conditions ◽  
Antibiotic Exposure ◽  
Biofilm Growth ◽  
Content Type ◽  
Potential Biomarker ◽  
Underlying Basis ◽  
Biofilm Development ◽  
Architecture Development

ABSTRACT Mycobacterium tuberculosis spontaneously grows at the air-medium interface, forming pellicle biofilms, which harbor more drug-tolerant persisters than planktonic cultures. The underlying basis for increased persisters in M. tuberculosis biofilms is unknown. Using a transposon sequencing (Tn-seq) approach, we show here that multiple genes that are necessary for fitness of M. tuberculosis cells within biofilms, but not in planktonic cultures, are also implicated in tolerance of bacilli to a diverse set of stressors and antibiotics. Thus, development of M. tuberculosis biofilms appears to be associated with an enrichment of population, in which challenging growth conditions within biofilm architecture select for cells that maintain intrinsic tolerance to exogenous stresses, including antibiotic exposure. We further observed that the intrinsic drug tolerance of constituent cells of a biofilm determines the frequency of persisters. These findings together allow us to propose that the selection of elite cells during biofilm development promotes the frequency of persisters. Furthermore, probing the possibility that the population enrichment is an outcome of unique environment within biofilms, we demonstrate biofilm-specific induction in the synthesis of isonitrile lipopeptide (INLP). Mutation analysis indicates that INLP is necessary for the architecture development of M. tuberculosis biofilms. In summary, this study offers an insight into persistence of M. tuberculosis biofilms under antibiotic exposure, while identifying INLP as a potential biomarker for further investigation of this phenomenon.

scholarly journals The Pseudomonas aeruginosa CreBC Two-Component System Plays a Major Role in the Response to β-Lactams, Fitness, Biofilm Growth, and Global Regulation

2014 ◽  
Vol 58 (9) ◽  
pp. 5084-5095 ◽  
Author(s):  
Laura Zamorano ◽  
Bartolomé Moyà ◽  
Carlos Juan ◽  
Xavier Mulet ◽  
Jesús Blázquez ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Anaerobic Respiration ◽  
Biofilm Growth ◽  
Content Type ◽  
Comprehensive Collection ◽  
Regulatory Systems ◽  
Two Component ◽  
Life Threatening ◽  
Inner Membrane Protein ◽  
Biofilm Development

ABSTRACTPseudomonas aeruginosais a ubiquitous versatile environmental microorganism with a remarkable ability to grow under diverse environmental conditions. Moreover,P. aeruginosais responsible for life-threatening infections in immunocompromised and cystic fibrosis patients, as the extraordinary capacity of this pathogen to develop antimicrobial resistance dramatically limits our therapeutic arsenal. Its large genome carries an outstanding number of genes belonging to regulatory systems, including multiple two-component sensor-regulator systems that modulate the response to the different environmental stimuli. Here, we show that one of two systems, designated CreBC (carbon source responsive) and BlrAB (β-lactam resistance), might be of particular relevance. We first identified the stimuli triggering the activation of the CreBC system, which specifically responds to penicillin-binding protein 4 (PBP4) inhibition by certain β-lactam antibiotics. Second, through an analysis of a large comprehensive collection of mutants, we demonstrate an intricate interconnection between the CreBC system, the peptidoglycan recycling pathway, and the expression of the concerning chromosomal β-lactamase AmpC. Third, we show that the CreBC system, and particularly its effector inner membrane protein CreD, plays a major role in bacterial fitness and biofilm development, especially in the presence of subinhibitory concentrations of β-lactams. Finally, global transcriptomics reveals broad regulatory functions of CreBC in basic physiological aspects, particularly anaerobic respiration, in both the presence and absence of antibiotics. Therefore, the CreBC system is envisaged as a potentially interesting target for improving the efficacy of β-lactams againstP. aeruginosainfections.

scholarly journals Changes in Microbial Biofilm Communities during Colonization of Sewer Systems

2015 ◽  
Vol 81 (20) ◽  
pp. 7271-7280 ◽  
Author(s):  
O. Auguet ◽  
M. Pijuan ◽  
J. Batista ◽  
C. M. Borrego ◽  
O. Gutierrez
Keyword(s):  
Time Course ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Full Scale ◽  
Molecular Techniques ◽  
Rrna Gene ◽  
Process Data ◽  
Microbial Biofilm ◽  
Biofilm Growth ◽  
Content Type ◽  
Biofilm Development

ABSTRACTThe coexistence of sulfate-reducing bacteria (SRB) and methanogenic archaea (MA) in anaerobic biofilms developed in sewer inner pipe surfaces favors the accumulation of sulfide (H2S) and methane (CH4) as metabolic end products, causing severe impacts on sewerage systems. In this study, we investigated the time course of H2S and CH4production and emission rates during different stages of biofilm development in relation to changes in the composition of microbial biofilm communities. The study was carried out in a laboratory sewer pilot plant that mimics a full-scale anaerobic rising sewer using a combination of process data and molecular techniques (e.g., quantitative PCR [qPCR], denaturing gradient gel electrophoresis [DGGE], and 16S rRNA gene pyrotag sequencing). After 2 weeks of biofilm growth, H2S emission was notably high (290.7 ± 72.3 mg S-H2S liter−1day−1), whereas emissions of CH4remained low (17.9 ± 15.9 mg COD-CH4liter−1day−1). This contrasting trend coincided with a stable SRB community and an archaeal community composed solely of methanogens derived from the human gut (i.e.,MethanobrevibacterandMethanosphaera). In turn, CH4emissions increased after 1 year of biofilm growth (327.6 ± 16.6 mg COD-CH4liter−1day−1), coinciding with the replacement of methanogenic colonizers by species more adapted to sewer conditions (i.e.,Methanosaetaspp.). Our study provides data that confirm the capacity of our laboratory experimental system to mimic the functioning of full-scale sewers both microbiologically and operationally in terms of sulfide and methane production, gaining insight into the complex dynamics of key microbial groups during biofilm development.

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