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

Vibrio harveyi 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 V. harveyi from the seawater environment to host fish muscle environment. The comprehensive transcriptome analysis revealed dramatic changes in the transcriptome of V. harveyi 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 V. harveyi's adaptation to host fish muscle. A comparison of biological phenotypes revealed that V. harveyi 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 V. harveyi from seawater to the muscle of the host fish. [ABSTRACT FROM AUTHOR]