文摘
Vibrio parahaemolyticus is a halophilic bacterium that causes seafood-borne gastroenteritis which can occur through direct or cross-contamination. In this study, biosurfactant-producing marine bacteria were isolated from 28 soil samples collected from mangrove and coastal regions. Using the cross streak technique, 26 isolates were found to inhibit the growth of V. parahaemolyticus. Biosurfactant lipopeptides were obtained by acid precipitation and their antimicrobial potentials were assessed by the agar well diffusion technique. The extract of a bacterial isolate SM11 derived from mangrove soil showed the strongest inhibitory activity against V. parahaemolyticus. The inhibition zones against V. parahaemolyticus of the extract obtained by chloroform and methanol at concentrations of 900, 1800 and 2600 μg/mL were 16.9 ± 0.2, 18.4 ± 0.5 and 25.0 ± 0.1 mm, respectively. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract were 256 to 512 and 512 to 1024 μg/mL, respectively. The extract of biosurfactants showed more than 60 % reduction in V. parahaemolyticus adhesion. 16S rRNA gene sequencing of SM11 revealed that this isolate is Bacillus amyloliquefaciens. The active fractions obtained from anion exchange chromatography and HPLC as analysed by ESI-Q-TOF mass spectrometry indicated that those biosurfactants were mycosubtilin, surfactin and iturin A. Besides highlighting the merits of biosurfactants as antagonistic agents, this study suggests the possibility of using them to decrease cross-contamination of V. parahaemolyticus on cooking or food processing surfaces.KeywordsBiosurfactantsVibrio parahaemolyticusBacillus amyloliquefaciensMycosubtilinSurfactinIturin A