Roles of flgJ in biofilm formation of Vibrio alginolyticus.

Aim: This study aimed to investigate the role of two flgJ genes in flagellar assembly and biofilm regulation in Vibrio alginolyticus.

Methods And Results: To investigate the functions of the flgJ, overexpression and gene knockout techniques were employed. Overexpression of flgJ1 enhanced the strain's growth capacity, leading to a rapid bacterial concentration that initiated biofilm formation. Additionally, this overexpression caused different aggregation patterns at various growth stages. In contrast, the knockout of flgJ1 resulted in the loss of the flagellum, reduced motility, and decreased growth. Interestingly, under static culture conditions, the flgJ1 mutant strain aggregated and grew at the air-liquid interface, accompanied by an increased concentration of intracellular c-di-GMP, which ultimately also promoted biofilm formation. Thus, both the absence and overexpression of flgJ1 led to increased biofilm formation. On the other hand, both gene knockout and overexpression of flgJ2 lacked any response under the experimental conditions.

Conclusion: FlgJ1 plays a crucial role in flagellar assembly and motility, while flgJ2 has been found to be non-functional. Both overexpression and knockout of the flgJ1 gene result in increased biofilm formation through distinct regulatory mechanisms. These findings enhance our understanding of the role of flgJ gene in regulating biofilm formation.