Abstract
Bacteroides fragilis constitutes 1–2% of the natural microbiota of the human digestive tract and is the predominant anaerobic opportunistic pathogen in gastrointestinal infections. Most bacteria use quorum sensing (QS) to monitor cell density in relation to other cells and their environment. In Gram-negative bacteria, the LuxRI system is common. The luxR gene encodes a transcriptional activator inducible by type I acyl-homoserine lactone autoinducers (e.g., N-[3-oxohexanoyl] homoserine lactone and hexanoyl homoserine lactone [C6-HSL]). This study investigated the presence of QS system(s) in B. fragilis. The genome of American-type culture collection strain no. ATCC25285 was searched for QS genes. The strain was grown to late exponential phase in the presence or absence of synthetic C6-HSL and C8-HSL or natural homoserine lactones from cell-free supernatants from spent growth cultures of other bacteria. Growth, susceptibility to antimicrobial agents, efflux pump gene (bmeB) expression, and biofilm formation were measured. Nine luxR and no luxI orthologues were found. C6-HSL and supernatants from Yersinia enterocolitica, Vibrio cholerae, and Pseudomonas aeruginosa caused a significant (1) reduction in cellular density and (2) increases in expression of four putative luxR genes, bmeB3, bmeB6, bmeB7, and bmeB10, resistance to various antibiotics, which was reduced by carbonyl cyanide-m-chlorophenyl hydrazone (CCCP, an uncoupler that dissipates the transmembrane proton gradient, which is also the driving force of resistance nodulation division efflux pumps) and (3) increase in biofilm formation. Susceptibility of ATCC25285 to C6-HSL was also reduced by CCCP. These data suggest that (1) B. fragilis contains putative luxR orthologues, which could respond to exogenous homoserine lactones and modulate biofilm formation, bmeB efflux pump expression, and susceptibility to antibiotics, and (2) BmeB efflux pumps could transport homoserine lactones.
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References
Atunes LC, Ferreira QL, Ferreira OE, Rodrigues MK, Santos E, Avelar K, Pilotto MC, Ferreira CSM (2005) Bacteroides species produce Vibrio harveyi autoinducer 2-related molecules. Anaerobe 11:295–301
Balestrino D, Haagensen AJ, Rich C, Forestier C (2005) Characterization of type 2 quorum sensing in Klebsiella pneumoniae. J Bacteriol 187:2870–2880
Michael B, Smith JN, Swift S, Hefron F, Ahmer BM (2001) SdiA of Salmonella enterica is a LuxR homologue that detects mixed microbial communities. J Bact 183:5733–5742
Burgess NA, Kirke DF, Williams P, Winzer K, Hardie KR, Meyers NL, Aduse-Opoku J, Curtis MA, Cámara M (2002) LuxS-dependent quorum sensing in Porphyromonas gingivalis modulates protease and haemagglutinin activities but is not essential for virulence. Microbiology 148:763–772
Cerdeno-Tarraga AM, Patrick S, Crossman LC (2005) Extensive DNA inversions in the B. fragilis genome control variable gene expression. Science 307:1463–1465
Chan YY, Bian HS, Tan TMC (2007) Control of quorum sensing by a Burkholderia pseudomallei multidrug efflux pump. J Bacteriol 189:4320–4324
Clarke MB, Sperandio V (2004) Events at the host-microbial interface of the gastrointestinal tract III. Cell signaling among microbial flora, host and pathogens: there is a whole lot of talking going on. Am J Physiol Gastrointest Liver Physiol 288:1105–1109
Delisa MP, Wu CF, Wang L, Valdes JJ, Bentley WE (2001) DNA microarray-based identification of genes controlled by autoinducer 2-stimulated quorum sensing in Escherichia coli. J Bacteriol 183:5239–5247
Gray KM, Garey JR (2001) The evolution of bacterial LuxI and LuxR quorum sensing regulators. Microbiol 147:2379–2387
Hammer BK, Bassler BL (2003) Quorum sensing controls biofilm formation in Vibrio cholerae. Mol Microbiol 50:101–114
Kaper JB, Sperandio V (2005) Bacterial cell-to-cell signaling in the gastrointestinal tract. Infect Immun 73:3197–3209
Lupp C, Urbanowski M, Greenberg EP, Ruby EG (2003) The Vibrio fischeri quorum-sensing systems ain and lux sequentially induce luminescence gene expression and are important for persistence in the squid host. Mol Micorbiol 50:319–331
Maseda H, Sadawa I, Saito K, Uchiyama H, Nakae T, Nomura N (2004) Enhancement of the mexAB-oprM efflux pump expression by a quorum sensing autoinducer and its cancellation by a regulator MexT, of the mexEF-oprN efflux pump operon in Pseudomonas aeruginosa. Antimicrob Agents Chemother 48:1320–1328
Macfarlane S, Woodmansey EJ, Macfarlane GT (2005) Colonization of mucin by human intestinal bacteria and establishment of biofilm communities in a two-stage continuous culture system. Appl Envir Microbiol 71:7483–7492
Murphy TM, Kirkman C (2002) Biofilm formation by nontypeable Haemophilus influenzae: strain variability, outer membrane antigen expression and role of pili. BMC Microbiol 2:7
Pumbwe L, Ueda O, Yoshimura F, Chang A, Smith RL, Wexler HM (2006) Bacteroides fragilis BmeABC efflux systems additively confer intrinsic antimicrobial resistance. J Antimicrob Chemother 58:37–46
Pumbwe L, Chang A, Smith RM, Wexler HM (2006) Clinical significance of overexpression of multiple RND-family efflux pumps in Bacteroides fragilis isolates. J Antimicrob Chemother 58:543–548
Pumbwe L, Wareham DW, Aduse-Opoku J, Brazier JS, Wexler HM (2007) Genetic analysis of mechanisms of multidrug resistance in a clinical isolate of Bacteroides fragilis. Clin Microbiol Infect 13:183–189
Rahmati S, Yang S, Davidson AL, Zechiedrich EL (2002) Control of the AcrAB multidrug efflux pump by quorum-sensing regulator SdiA. Mol Microbiol 43:677–685
Rasmussen TB, Bjarnsholt T, Skindersoe ME, Hentzer M, Kristoffersen P, Köte M, Nielsen J, Eberl L, Givskov M (2005) Screening for quorum-sensing inhibitors (QSI) by use of a novel genetic system, the QSI selector. J Bacteriol 187:1799–1814
Smith JN, Ahmer BM (2003) Detection of other microbial species by Salmonella: expression of the SdiA regulon. J Bacteriol 185:1357–1366
Sperandio V, Torres AG, Girón JA, Kaper JB (2001) Quorum sensing is a global regulatory mechanism in enterohemorrhagic Escherichia coli O157:H7. J Bacteriol 183:5187–5197
Saye DE (2007) Recurring and antimicrobial-resistant infections: considering the potential role of biofilms in clinical practice. Ostomy/Wound Manage 53:46–48
Surette MG, Bassler BL (1998) Quorum sensing in Escherichia coli and Salmonella typhimurium. Proc Natl Acad Sci USA 95:7046–7050
Ueda O, Wexler HM, Hirai K, Shibata Y, Yoshimura F, Fujimura S (2005) Sixteen homologs of the mex-type multidrug resistance efflux pump in Bacteroides fragilis. Antimicrob Agents Chemother 49:2807–2815
von Bodman SB, Ball JK, Faini MA, Herrera C, Minogue TD, Urbanowski ML, Stevens AM (2003) The quorum sensing Negative regulators EsaR and ExpREcc, homologues within the LuxR family, retain the ability to function as activators of transcription. J Bacteriol 185:7001–7007
Waters CM, Bassler BL (2005) Quorum Sensing: cell-to-cell communication in bacteria. Annu Rev Cell Dev Biol 21:319–346
Wexler HM, Molitoris DE, Jashnian F, Finegold SM (1991) Comparison of spiral gradient with conventional agar dilution for susceptibility testing of anaerobic bacteria. Antimicrob Agents Chemother 35:1196–1202
Weinacht KG, Roche H, Krinos CM, Coyne MJ, Parkhill J, Comstock LE (2004) Tyrosine site-specific recombinases mediate DNA inversions affecting the expression of outer surface proteins of Bacteroides fragilis. Mol Microbiol 53:1319–1330
Yang S, Lopez C, Zechiedrich LE (2006) Quorum sensing and multidrug transporters in Escherichia coli. Proc Natl Acad Sci USA 103:2386–2391
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This study was supported by Merit Review Funds from the Department of Veterans Affairs, USA.
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Pumbwe, L., Skilbeck, C.A. & Wexler, H.M. Presence of Quorum-sensing Systems Associated with Multidrug Resistance and Biofilm Formation in Bacteroides fragilis . Microb Ecol 56, 412–419 (2008). https://doi.org/10.1007/s00248-007-9358-3
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DOI: https://doi.org/10.1007/s00248-007-9358-3