Amino Acid-Induced Chemotaxis Plays a Key Role in the Adaptation of from Seawater to the Muscle of the Host Fish.

is a normal flora in natural marine habitats and a significant opportunistic pathogen in marine animals. This bacterium can cause a series of lesions after infecting marine animals, in which muscle necrosis and ulcers are the most common symptoms. This study explored the adaptation mechanisms of from the seawater environment to host fish muscle environment. The comprehensive transcriptome analysis revealed dramatic changes in the transcriptome of during its adaptation to the host fish muscle environment. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, flagellar assembly, oxidative phosphorylation, bacterial chemotaxis, and two-component systems play crucial roles in 's adaptation to host fish muscle. A comparison of biological phenotypes revealed that displayed a significant increase in flagellar length, swimming, twitching, chemotaxis, adhesion, and biofilm formation after induction by host fish muscle, and its dominant amino acids, especially bacterial chemotaxis induced by host muscle, Ala and Arg. It could be speculated that the enhancement of bacterial chemotaxis induced by amino acids plays a key role in the adaptation of from seawater to the muscle of the host fish.