Distribution and expression of virulence genes in potentially pathogenic bacteria isolated from seafood in Thailand

Abstract

Since seafood can be a reservoir for diverse pathogenic bacteria, the risk to human health associated with seafood merits evaluation. The potentially pathogenic bacteria were isolated from seafood in Thailand. The 40 obtained strains were distinguished by ERIC-PCR fingerprints and identified to the species level by the VITEK 2 system. Their 16S rRNA gene had 97.74–99.79% nucleotide sequence identities to those of bacteria in 11 genera including Aeromonas, Citrobacter, Enterobacter, Escherichia, Hafnia, Klebsiella, Morganella, Salmonella, Proteus, Providencia, and Vibrio. Among the eight detected virulence genes, the tlh gene was expressed under all conditions, which, contrary to the cnf2, LTI, ssaO, and vt2e genes. Nutrient enrichment had a positive effect on the expression of kfu and uge genes, as well as a negative effect on the expression of the csgD gene. NaCl conferred a positive effect on the expression of the uge gene but negatively affected the expression of the csgD gene.