Allyl isothiocyanate exerts bactericidal and anti-biofilm effects against Vibrio parahaemolyticus via global...

Allyl isothiocyanate (AITC), a bioactive compound found in various cruciferous vegetables including wasabi, exhibits potent antimicrobial properties against foodborne pathogens. This study demonstrates that AITC significantly inhibits the growth of Vibrio parahaemolyticus in both culture media and seafood matrices (minced shrimp). For mid-log phase planktonic and biofilm-embedded V. parahaemolyticus, AITC exerts potent bactericidal effects that intensify at higher concentrations (≥50 μg/ml) and longer exposure times. Crucially, AITC disrupts pre-formed biofilms on abiotic (e.g., polystyrene) and biotic (shrimp shell) surfaces, degrading extracellular matrices and dispersing embedded cells, as visualized by scanning electron microscopy (SEM). Sublethal AITC exposure (25 μg/ml) triggers extensive transcriptional reprogramming in V. parahaemolyticus RIMD2210633, downregulating 1299 genes, including key virulence determinants (e.g., T3SS1, T3SS2, T6SS2, and TDH), flagellar assembly components, exopolysaccharide (EPS) biosynthesis machinery, and type IV pili. Paradoxically, despite inhibiting swimming motility and biofilm formation, AITC upregulates cyclic di-GMP (c-di-GMP) synthesis, suggesting a stress-adaptive response. Collectively, these findings reveal that AITC combats V. parahaemolyticus through direct bactericidal activity, biofilm dismantling, and global downregulation of virulence and colonization-associated genes, with the observed c-di-GMP increase representing a stress-adaptive response whose functional significance requires further investigation. This work supports the potential of AITC as a natural strategy to enhance seafood safety and provides a mechanistic framework for its multi-target action.