Transcriptomics Reveals the Mechanism of High-Adhesive Bacillus Subtilis Inhibiting Fresh Fish Spoilage

Aquatic products are highly susceptible to spoilage caused by adherence of spoilage bacteria during storage, so it is crucial to develop new microecological preservatives. The probiotic B. subtilis can achieve potential preser-vation effects by adhering to the fish gut to regulate the amount of probiotic colonization in the flora. Here, we demonstrated the surface adhesion characteristics of B. subtilis and the mechanism of adhesion-associated gene -mediated adhesion; the regulation of B. subtilis adhesion ability by nitrogen and carbon sources, and the application of tilapia preservation. Our results revealed 10 B. subtilis adhesion-related genes, among which ni-trogen sources up-regulate the adhesion genes hag and motA, carbon sources up-regulate sinR and fliG. Based on flagellum-associated high adhesion strain C6 and high adhesion regulation of B. subtilis C6_H allowed the abundance of probiotic bacteria Bacillus, Rhodobacteraceae to increase, attenuate the content of spoilage flavor substances such as 1-Octen-3-ol, 15-Crown-5 and maintain the freshness of tilapia. The results helped to reveal the adhesion mechanism of B. subtilis and to develop and apply microecological preservatives with high quality adhesion ability.