Identification of oligopeptide permease (opp) gene cluster in Vibrio fluvialis and characterization of biofilm production by oppA knockout mutation

Oligopeptides play important roles in bacterial nutrition and signaling. The oligopeptide permease (opp) gene cluster was cloned from Vibrio fluvialis. The V fluvialis opp operon encodes five proteins: OppA, B, C, D and F. The deduced amino acid sequence of these proteins showed high similarity with those from other Gram-negative bacteria. To investigate whether OppA is involved in biofilm production, an opp A knockout mutant was constructed by homologous recombination. The opp A mutant produced more abundant biofilm than the wild type in BHI medium. When both strains were grown in minimal medium, we could not detect biofilm formation. However, it was found that the biofilm productivity of the opp A mutant was two folds greater than that of the wild type in minimal medium containing peptone or tryptone. This variation in biofilm production was demonstrated by scanning electron microscopy (SEM). In minimal medium containing C-sources, both strains produced some biofilm without significant difference in the biofilm productivity. Complementation of opp A gene with the plasmid pOAC2, which contains opp A ORF plus promoter regions, was sufficient to restore growth rate and biofilm to the wild type. These results suggest that the OppA protein is involved in uptake of peptides and affects biofilm productivity. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.