scholarly journals Acetic Acid Acts as a Volatile Signal To Stimulate Bacterial Biofilm Formation

mBio ◽  
2015 ◽  
Vol 6 (3) ◽  
Author(s):  
Yun Chen ◽  
Kevin Gozzi ◽  
Fang Yan ◽  
Yunrong Chai
Keyword(s):  
Acetic Acid ◽  
Bacillus Subtilis ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Biological Activities ◽  
Bacterial Biofilm ◽  
Acetic Acid Production ◽  
Content Type ◽  
Metabolic Signal

ABSTRACTVolatiles are small air-transmittable chemicals with diverse biological activities. In this study, we showed that volatiles produced by the bacteriumBacillus subtilishad a profound effect on biofilm formation of neighboringB. subtiliscells that grew in proximity but were physically separated. We further demonstrated that one such volatile, acetic acid, is particularly potent in stimulating biofilm formation. Multiple lines of genetic evidence based onB. subtilismutants that are defective in either acetic acid production or transportation suggest thatB. subtilisuses acetic acid as a metabolic signal to coordinate the timing of biofilm formation. Lastly, we investigated howB. subtiliscells sense and respond to acetic acid in regulating biofilm formation. We showed the possible involvement of three sets of genes (ywbHG,ysbAB, andyxaKC), all encoding putative holin-antiholin-like proteins, in cells responding to acetic acid and stimulating biofilm formation. All three sets of genes were induced by acetate. A mutant with a triple mutation of those genes showed a severe delay in biofilm formation, whereas a strain overexpressingywbHGshowed early and robust biofilm formation. Results of our studies suggest thatB. subtilisand possibly other bacteria use acetic acid as a metabolic signal to regulate biofilm formation as well as a quorum-sensing-like airborne signal to coordinate the timing of biofilm formation by physically separated cells in the community.IMPORTANCEVolatiles are small, air-transmittable molecules produced by all kingdoms of organisms including bacteria. Volatiles possess diverse biological activities and play important roles in bacteria-bacteria and bacteria-host interactions. Although volatiles can be used as a novel and important way of cell-cell communication due to their air-transmittable nature, little is known about how the volatile-mediated signaling mechanism works. In this study, we demonstrate that the bacteriumBacillus subtilisuses one such volatile, acetic acid, as a quorum-sensing-like signal to coordinate the timing of the formation of structurally complex cell communities, also known as biofilms. We further characterized the molecular mechanisms of howB. subtilisresponds to acetic acid in stimulating biofilm formation. Our study also suggests that acetic acid may be used as a volatile signal for cross-species communication.

scholarly journals LitR of Vibrio salmonicida Is a Salinity-Sensitive Quorum-Sensing Regulator of Phenotypes Involved in Host Interactions and Virulence

2012 ◽  
Vol 80 (5) ◽  
pp. 1681-1689 ◽  
Author(s):  
Ane Mohn Bjelland ◽  
Henning Sørum ◽  
Daget Ayana Tegegne ◽  
Hanne C. Winther-Larsen ◽  
Nils Peder Willassen ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Cold Water ◽  
Bacterial Species ◽  
Cell Communication ◽  
Cell Aggregation ◽  
Fish Host ◽  
Content Type ◽  
Vibrio Salmonicida

ABSTRACTVibrio(Aliivibrio)salmonicidais the causal agent of cold-water vibriosis, a fatal bacterial septicemia primarily of farmed salmonid fish. The molecular mechanisms of invasion, colonization, and growth ofV. salmonicidain the host are still largely unknown, and few virulence factors have been identified. Quorum sensing (QS) is a cell-to-cell communication system known to regulate virulence and other activities in several bacterial species. The genome ofV. salmonicidaLFI1238 encodes products presumably involved in several QS systems. In this study, the gene encoding LitR, a homolog of the master regulator of QS inV. fischeri, was deleted. Compared to the parental strain, thelitRmutant showed increased motility, adhesion, cell-to-cell aggregation, and biofilm formation. Furthermore, thelitRmutant produced less cryptic bioluminescence, whereas production of acylhomoserine lactones was unaffected. Our results also indicate a salinity-sensitive regulation of LitR. Finally, reduced mortality was observed in Atlantic salmon infected with thelitRmutant, implying that the fish were more susceptible to infection with the wild type than with the mutant strain. We hypothesize that LitR inhibits biofilm formation and favors planktonic growth, with the latter being more adapted for pathogenesis in the fish host.

scholarly journals The RapP-PhrP Quorum-Sensing System of Bacillus subtilis Strain NCIB3610 Affects Biofilm Formation through Multiple Targets, Due to an Atypical Signal-Insensitive Allele of RapP

2014 ◽  
Vol 197 (3) ◽  
pp. 592-602 ◽  
Author(s):  
Shira Omer Bendori ◽  
Shaul Pollak ◽  
Dorit Hizi ◽  
Avigdor Eldar
Keyword(s):  
Bacillus Subtilis ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Response Regulator ◽  
Subtilis Strain ◽  
Transcriptional Level ◽  
Response Regulators ◽  
Multiple Targets ◽  
Content Type ◽  
Negative Effect

The genome ofBacillus subtilis168 encodes eightrap-phrquorum-sensing pairs. Rap proteins of all characterized Rap-Phr pairs inhibit the function of one or several important response regulators: ComA, Spo0F, or DegU. This inhibition is relieved upon binding of the peptide encoded by the cognatephrgene.Bacillus subtilisstrain NCIB3610, the biofilm-proficient ancestor of strain 168, encodes, in addition, therapP-phrPpair on the plasmid pBS32. RapP was shown to dephosphorylate Spo0F and to regulate biofilm formation, but unlike other Rap-Phr pairs, RapP does not interact with PhrP. In this work we extend the analysis of the RapP pathway by reexamining its transcriptional regulation, its effect on downstream targets, and its interaction with PhrP. At the transcriptional level, we show thatrapPandphrPregulation is similar to that of otherrap-phrpairs. We further find that RapP has an Spo0F-independent negative effect on biofilm-related genes, which is mediated by the response regulator ComA. Finally, we find that the insensitivity of RapP to PhrP is due to a substitution of a highly conserved residue in the peptide binding domain of therapPallele of strain NCIB3610. Reversing this substitution to the consensus amino acid restores the PhrP dependence of RapP activity and eliminates the effects of therapP-phrPlocus on ComA activity and biofilm formation. Taken together, our results suggest that RapP strongly represses biofilm formation through multiple targets and that PhrP does not counteract RapP due to a rare mutation inrapP.

scholarly journals Multiple Drug-Induced Stress Responses Inhibit Formation of Escherichia coli Biofilms

2020 ◽  
Vol 86 (21) ◽  
Author(s):  
Nataliya A. Teteneva ◽  
Sergey V. Mart’yanov ◽  
María Esteban-López ◽  
Jörg Kahnt ◽  
Timo Glatter ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stress Responses ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Drug Repurposing ◽  
Bacterial Attachment ◽  
Bacterial Biofilm ◽  
Multiple Drug ◽  
Content Type ◽  
Approved Drugs

ABSTRACT In most ecosystems, bacteria exist primarily as structured surface-associated biofilms that can be highly tolerant to antibiotics and thus represent an important health issue. Here, we explored drug repurposing as a strategy to identify new antibiofilm compounds, screening over 1,000 compounds from the Prestwick Chemical Library of approved drugs for specific activities that prevent biofilm formation by Escherichia coli. Most growth-inhibiting compounds, which include known antibacterial but also antiviral and other drugs, also reduced biofilm formation. However, we also identified several drugs that were biofilm inhibitory at doses where only a weak effect or no effect on planktonic growth could be observed. The activities of the most specific antibiofilm compounds were further characterized using gene expression analysis, proteomics, and microscopy. We observed that most of these drugs acted by repressing genes responsible for the production of curli, a major component of the E. coli biofilm matrix. This repression apparently occurred through the induction of several different stress responses, including DNA and cell wall damage, and homeostasis of divalent cations, demonstrating that biofilm formation can be inhibited through a variety of molecular mechanisms. One tested drug, tyloxapol, did not affect curli expression or cell growth but instead inhibited biofilm formation by suppressing bacterial attachment to the surface. IMPORTANCE The prevention of bacterial biofilm formation is one of the major current challenges in microbiology. Here, by systematically screening a large number of approved drugs for their ability to suppress biofilm formation by Escherichia coli, we identified a number of prospective antibiofilm compounds. We further demonstrated different mechanisms of action for individual compounds, from induction of replicative stress to disbalance of cation homeostasis to inhibition of bacterial attachment to the surface. Our work demonstrates the potential of drug repurposing for the prevention of bacterial biofilm formation and suggests that also for other bacteria, the activity spectrum of antibiofilm compounds is likely to be broad.

scholarly journals ThePseudomonas aeruginosaPrrF1 and PrrF2 Small Regulatory RNAs Promote 2-Alkyl-4-Quinolone Production through Redundant Regulation of theantRmRNA

2018 ◽  
Vol 200 (10) ◽  
Author(s):  
Louise Djapgne ◽  
Subrata Panja ◽  
Luke K. Brewer ◽  
Jonathan H. Gans ◽  
Maureen A. Kane ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Biological Activities ◽  
Content Type ◽  
Downstream Effects ◽  
Infection Models ◽  
Small Regulatory Rnas ◽  
Regulatory Rnas ◽  
Translational Start

ABSTRACTPseudomonas aeruginosais an opportunistic Gram-negative pathogen that requires iron for growth and virulence. Under low-iron conditions,P. aeruginosatranscribes two highly identical (95%) small regulatory RNAs (sRNAs), PrrF1 and PrrF2, which are required for virulence in acute murine lung infection models. The PrrF sRNAs promote the production of 2-akyl-4(1H)-quinolone metabolites (AQs) that mediate a range of biological activities, including quorum sensing and polymicrobial interactions. Here, we show that the PrrF1 and PrrF2 sRNAs promote AQ production by redundantly inhibiting translation ofantR, which encodes a transcriptional activator of the anthranilate degradation genes. A combination of genetic and biophysical analyses was used to define the sequence requirements for PrrF regulation ofantR, demonstrating that the PrrF sRNAs interact with theantR5′ untranslated region (UTR) at sequences overlapping the translational start site of this mRNA. TheP. aeruginosaHfq protein interacted with UA-rich sequences in both PrrF sRNAs (Kd[dissociation constant] = 50 nM and 70 nM). Hfq bound with lower affinity to theantRmRNA (0.3 μM), and PrrF was able to bind toantRmRNA in the absence of Hfq. Nevertheless, Hfq increased the rate of PrrF annealing to theantRUTR by 10-fold. These studies provide a mechanistic description of how the PrrF1 and PrrF2 sRNAs mediate virulence traits, such as AQ production, inP. aeruginosa.IMPORTANCEThe iron-responsive PrrF sRNAs play a central role in regulatingP. aeruginosairon homeostasis and pathogenesis, yet the molecular mechanisms by which PrrF regulates gene expression are largely unknown. In this study, we used genetic and biophysical analyses to define the interactions of the PrrF sRNAs with Hfq, an RNA annealer, and theantRmRNA, which has downstream effects on quorum sensing and virulence factor production. These studies provide a comprehensive mechanistic analysis of how the PrrF sRNAs regulate virulence trait production through a key mRNA target inP. aeruginosa.

scholarly journals Role of Glutamate Synthase in Biofilm Formation by Bacillus subtilis

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Tan Kimura ◽  
Kazuo Kobayashi
Keyword(s):  
Bacillus Subtilis ◽  
Biofilm Formation ◽  
Citrate Synthase ◽  
Glutamate Synthase ◽  
Tca Cycle ◽  
Bacterial Biofilm ◽  
Dependent Manner ◽  
Metabolic System ◽  
Content Type ◽  
Metabolic Systems

ABSTRACT Bacillus subtilis forms robust biofilms in the presence of large amounts of carbon sources, such as glycerol. However, little is known about the importance of the metabolic systems, or the relationship between metabolic systems and regulatory systems, involved in biofilm formation. Glutamate synthase, encoded by gltAB, is an enzyme that converts 2-ketoglutarate (a tricarboxylic acid [TCA] cycle intermediate) and glutamine into glutamate, which is a general amino group donor in metabolism. Here, we show that a ΔgltA mutant exhibited early arrest of biofilm formation in complex medium containing glycerol. This phenotype was not due to glutamate auxotrophy. Consistent with its biofilm formation phenotype, the ΔgltA mutant exhibited an early decrease in expression of the epsA and tapA operons, which are responsible for production of biofilm matrix polymers. This resulted from decreased activity of their regulator, Spo0A, as evidenced by reduced expression of other Spo0A-regulated genes in the ΔgltA mutant. The ΔgltA mutation prevented biofilm formation only in the presence of large amounts of glycerol. Moreover, limited expression of citrate synthase (but not other TCA enzymes) restored biofilm-forming ability to the ΔgltA mutant. These results indicate that the ΔgltA mutant accumulates an inhibitory intermediate (citrate) in the TCA cycle in the presence of large amounts of glycerol. The ΔgltA mutant formed biofilms when excess iron was added to the medium. Taken together, the data suggest that accumulation of citrate ions by the ΔgltA mutant causes iron shortage due to chelation, which prevents activation of Spo0A and causes defective biofilm formation. IMPORTANCE Bacillus subtilis, a model organism for bacterial biofilm formation, forms robust biofilms in a medium-dependent manner. Although the regulatory network that controls biofilm formation has been well studied, the importance of the underlying metabolic systems remains to be elucidated. The present study demonstrates that a metabolic disorder in a well-conserved metabolic system causes accumulation of an inhibitory metabolic intermediate that prevents activation of the system that regulates biofilm formation. These findings increase our understanding of the coordination between cellular metabolic status and the regulatory networks governing biofilm formation.

scholarly journals Negative Interplay between Biofilm Formation and Competence in the Environmental Strains of Bacillus subtilis

mSystems ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Qianxuan She ◽  
Evan Hunter ◽  
Yuxuan Qin ◽  
Samantha Nicolau ◽  
Eliza A. Zalis ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Cell Differentiation ◽  
Biofilm Formation ◽  
Competence Development ◽  
Bacterial Biofilm ◽  
Soil Bacterium ◽  
Natural Competence ◽  
Content Type ◽  
Pathway Regulation

The soil bacterium Bacillus subtilis can form robust biofilms, which are important for its survival in the environment. B. subtilis also exhibits natural competence. By investigating competence development in B. subtilis in situ during biofilm formation, we reveal that robust biofilm formation often greatly reduces the frequency of competent cells within the biofilm. We then characterize a cross-pathway regulation that allows cells in these two developmental events to undergo mutually exclusive cell differentiation during biofilm formation. Finally, we discuss potential biological implications of limiting competence in a bacterial biofilm.

scholarly journals Structure-Function Studies of the Bacillus subtilis Ric Proteins Identify the Fe-S Cluster-Ligating Residues and Their Roles in Development and RNA Processing

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Felix Adusei-Danso ◽  
Faisal Tarique Khaja ◽  
Micaela DeSantis ◽  
Philip D. Jeffrey ◽  
Eugenie Dubnau ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Stable Complex ◽  
Cysteine Residues ◽  
Major Step ◽  
Content Type ◽  
C Terminus ◽  
Cluster 2

ABSTRACT In Bacillus subtilis, the RicA (YmcA), RicF (YlbF), and RicT (YaaT) proteins accelerate the phosphorylation of the transcription factor Spo0A, contributing to genetic competence, sporulation, and biofilm formation, and are also essential for the correct maturation of several protein-encoding and riboswitch RNAs. These proteins form a stable complex (RicAFT) that carries two [4Fe-4S]+2 clusters. We show here that the complex is a 1:1:1 heterotrimer, and we present the X-ray crystal structures of a RicAF heterotetramer and of a RicA dimer. We also demonstrate that one of the Fe-S clusters (cluster 1) is ligated by cysteine residues donated exclusively by RicT and can be retained when the RicT monomer is purified by itself. Cluster 2 is ligated by C167 from RicT, by C134 and C146 located near the C terminus of RicF, and by C141 at the C terminus of RicA. These findings imply the following novel arrangement: adjacent RicT residues C166 and 167 ligate clusters 1 and 2, respectively, while cluster 2 is ligated by cysteine residues from RicT, RicA, and RicF. Thus, the two clusters must lie close to one another and at the interface of the RicAFT protomers. We also show that the cluster-ligating cysteine residues, and therefore most likely both Fe-S clusters, are essential for cggR-gapA mRNA maturation, for the regulation of ricF transcript stability, and for several Ric-associated developmental phenotypes, including competence for transformation, biofilm formation, and sporulation. Finally, we present evidence that RicAFT, RicAF, and RicA and the RicT monomer may play distinct regulatory roles in vivo. IMPORTANCE The RicA, RicF, and RicT proteins are widely conserved among the firmicute bacteria and play multiple roles in Bacillus subtilis. Among the phenotypes associated with the inactivation of these proteins are the inability to be genetically transformed or to form biofilms, a decrease in sporulation frequency, and changes in the stability and maturation of multiple RNA species. Despite their importance, the molecular mechanisms of Ric protein activities have not been elucidated and the roles of the two iron-sulfur clusters on the complex of the three proteins are not understood. To unravel the mechanisms of Ric action, molecular characterization of the complex and of its constituent proteins is essential. This report represents a major step toward understanding the structures of the Ric proteins, the arrangement and roles of the Fe-S clusters, and the phenotypes associated with Ric mutations.

scholarly journals Diversification of the AlpB Outer Membrane Protein of Helicobacter pylori Affects Biofilm Formation and Cellular Adhesion

2016 ◽  
Vol 199 (6) ◽  
Author(s):  
Hideo Yonezawa ◽  
Takako Osaki ◽  
Toshiyuki Fukutomi ◽  
Tomoko Hanawa ◽  
Satoshi Kurata ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Bacterial Biofilm ◽  
Content Type ◽  
Successful Infection ◽  
H Pylori

ABSTRACT Helicobacter pylori is one of the most common causes of bacterial infection in humans, and it forms biofilms on human gastric mucosal epithelium as well as on in vitro abiotic surfaces. Bacterial biofilm is critical not only for environmental survival but also for successful infection. We previously demonstrated that strain TK1402, which was isolated from a Japanese patient with duodenal and gastric ulcers, has high biofilm-forming ability in vitro relative to other strains. In addition, we showed that outer membrane vesicles (OMV) play an important role in biofilm formation. The aim of this study was to analyze which protein(s) in the OMV contributes to biofilm formation in TK1402. We obtained a spontaneous mutant strain derived from TK1402 lacking biofilm-forming ability. The protein profiles of the OMV were compared between this mutant strain and the wild type, and it was found that AlpB, an outer membrane protein in the OMV of the mutant strain, was markedly decreased compared to that of the wild type. Restoration of TK1402 alpB to the mutant strain fully recovered the ability to form biofilm. However, restoration with alpB from other strains demonstrated incomplete recovery of biofilm-forming ability. We therefore inferred that the variable region of AlpB (amino acid positions 121 to 146) was involved in TK1402 biofilm formation. In addition, diversification of the AlpB sequence was shown to affect the ability to adhere to AGS cells. These results demonstrate a new insight into the molecular mechanisms of host colonization by H. pylori. IMPORTANCE Bacterial biofilm is critical not only for environmental survival but also for successful infection. The mechanism of Helicobacter pylori adherence to host cells mediated by cell surface adhesins has been the focus of many studies, but little is known regarding factors involved in H. pylori biofilm formation. Our study demonstrated that AlpB plays an important role in biofilm formation and that this property depends upon the specific sequence of alpB. This in turn was shown to be important in the ability to adhere to gastric cells. We anticipate that these results will provide new insight into the molecular mechanisms of H. pylori colonization.

scholarly journals Selective Pressure for Biofilm Formation in Bacillus subtilis: Differential Effect of Mutations in the Master Regulator SinR on Bistability

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Jan Kampf ◽  
Jan Gerwig ◽  
Kerstin Kruse ◽  
Robert Cleverley ◽  
Miriam Dormeyer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Selective Pressure ◽  
Wild Type ◽  
Master Regulator ◽  
Form Complex ◽  
Content Type

ABSTRACT Biofilm formation by Bacillus subtilis requires the expression of genes encoding enzymes for extracellular polysaccharide synthesis and for an amyloid-like protein. The master regulator SinR represses all the corresponding genes, and repression of these key biofilm genes is lifted when SinR interacts with its cognate antagonist proteins. The YmdB phosphodiesterase is a recently discovered factor that is involved in the control of SinR activity: cells lacking YmdB exhibit hyperactive SinR and are unable to relieve the repression of the biofilm genes. In this study, we have examined the dynamics of gene expression patterns in wild-type and ymdB mutant cells by microfluidic analysis coupled to time-lapse microscopy. Our results confirm the bistable expression pattern for motility and biofilm genes in the wild-type strain and the loss of biofilm gene expression in the mutant. Moreover, we demonstrated dynamic behavior in subpopulations of the wild-type strain that is characterized by switches in sets of the expressed genes. In order to gain further insights into the role of YmdB, we isolated a set of spontaneous suppressor mutants derived from ymdB mutants that had regained the ability to form complex colonies and biofilms. Interestingly, all of the mutations affected SinR. In some mutants, large genomic regions encompassing sinR were deleted, whereas others had alleles encoding SinR variants. Functional and biochemical studies with these SinR variants revealed how these proteins allowed biofilm gene expression in the ymdB mutant strains. IMPORTANCE Many bacteria are able to choose between two mutually exclusive lifestyles: biofilm formation and motility. In the model bacterium Bacillus subtilis, this choice is made by each individual cell rather than at the population level. The transcriptional repressor SinR is the master regulator in this decision-making process. The regulation of SinR activity involves complex control of its own expression and of its interaction with antagonist proteins. We show that the YmdB phosphodiesterase is required to allow the expression of SinR-repressed genes in a subpopulation of cells and that such subpopulations can switch between different SinR activity states. Suppressor analyses revealed that ymdB mutants readily acquire mutations affecting SinR, thus restoring biofilm formation. These findings suggest that B. subtilis cells experience selective pressure to form the extracellular matrix that is characteristic of biofilms and that YmdB is required for the homeostasis of SinR and/or its antagonists.

Sign in / Sign up

Export Citation Format

Share Document