Sublethal Curcumin Exposure Induces Global Gene Expression and Biofilm-Related Phenotypic Changes in Vibrio parahaemolyticus.

Vibrio parahaemolyticus, a foodborne pathogen found in marine environments, is susceptible to the antimicrobial effects of curcumin-a lipophilic polyphenolic pigment with diverse biological activities. While sublethal doses of curcumin inhibit behaviors of V. parahaemolyticus, the underlying molecular mechanisms remain poorly characterized. In this study, we aimed to investigate the impact of sublethal doses of curcumin on gene expression and key bacterial processes in V. parahaemolyticus. RNA sequencing (RNA-seq) revealed that sublethal curcumin concentrations significantly suppressed bacterial growth and altered the expression of 788 genes. These differentially expressed genes (DEGs) were associated with critical pathways, including upregulated systems such as polar flagellum, type IV pili, and type VI secretion systems (T6SS1 and T6SS2), as well as downregulated systems such as lateral flagella, exopolysaccharides (EPS), and type III secretion systems (T3SS1 and T3SS2). Notably, most DEGs involved in cyclic di-GMP (c-di-GMP) metabolism were downregulated, while putative porin-related genes were upregulated. Additionally, sublethal curcumin significantly inhibited biofilm formation and swimming motility but enhanced c-di-GMP production in V. parahaemolyticus. This study provides valuable insights into how V. parahaemolyticus adjusts its gene expression in response to sublethal levels of curcumin.