PMID:17483266
| Citation |
Lee, J, Bansal, T, Jayaraman, A, Bentley, WE and Wood, TK (2007) Enterohemorrhagic Escherichia coli biofilms are inhibited by 7-hydroxyindole and stimulated by isatin. Appl. Environ. Microbiol. 73:4100-9 |
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| Abstract |
Since indole is present at up to 500 microM in the stationary phase and is an interspecies biofilm signal (J. Lee, A. Jayaraman, and T. K. Wood, BMC Microbiol. 7:42, 2007), we investigated hydroxyindoles as biofilm signals and found them also to be nontoxic interspecies biofilm signals for enterohemorrhagic Escherichia coli O157:H7 (EHEC), E. coli K-12, and Pseudomonas aeruginosa. The genetic basis of EHEC biofilm formation was also explored, and notably, virulence genes in biofilm cells were repressed compared to those in planktonic cells. In Luria-Bertani medium (LB) on polystyrene with quiescent conditions, 7-hydroxyindole decreased EHEC biofilm formation 27-fold and decreased K-12 biofilm formation 8-fold without affecting the growth of planktonic cells. 5-Hydroxyindole also decreased biofilm formation 11-fold for EHEC and 6-fold for K-12. In contrast, isatin (indole-2,3-dione) increased biofilm formation fourfold for EHEC, while it had no effect for K-12. When continuous-flow chambers were used, confocal microscopy revealed that EHEC biofilm formation was reduced 6-fold by indole and 10-fold by 7-hydroxyindole in LB. Whole-transcriptome analysis revealed that isatin represses indole synthesis by repressing tnaABC 7- to 37-fold in EHEC, and extracellular indole levels were found to be 20-fold lower. Furthermore, isatin repressed the AI-2 transporters lsrABCDFGKR, while significantly inducing the flagellar genes flgABCDEFGHIJK and fliAEFGILMNOPQ (which led to a 50% increase in motility). 7-Hydroxyindole induces the biofilm inhibitor/stress regulator ycfR and represses cysADIJPU/fliC (which led to a 50% reduction in motility) and purBCDEFHKLMNRT. Isogenic mutants showed that 7-hydroxyindole inhibits E. coli biofilm through cysteine metabolism. 7-Hydroxyindole (500 microM) also stimulates P. aeruginosa PAO1 biofilm formation twofold; therefore, hydroxyindoles are interspecies bacterial signals, and 7-hydroxyindole is a potent EHEC biofilm inhibitor. |
| Links |
PubMed PMC1932762 Online version:10.1128/AEM.00360-07 |
| Keywords |
Base Sequence; Biofilms/drug effects; Biofilms/growth & development; Cysteine/metabolism; DNA Primers/genetics; DNA, Bacterial/genetics; Escherichia coli K12/drug effects; Escherichia coli K12/genetics; Escherichia coli K12/growth & development; Escherichia coli O157/drug effects; Escherichia coli O157/genetics; Escherichia coli O157/pathogenicity; Escherichia coli O157/physiology; Gene Expression/drug effects; Genes, Bacterial/drug effects; Humans; Indoles/pharmacology; Isatin/pharmacology; Movement/drug effects; Mutation; Pseudomonas aeruginosa/drug effects; Pseudomonas aeruginosa/genetics; Pseudomonas aeruginosa/growth & development; Signal Transduction |
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