Characterizing a Novel Mechanism Regulating Swarming Behavior in Vibrio parahaemolyticus

Abstract

Quorum sensing (QS) is a process of bacterial communication that enables coordination of group behaviors. QS plays a central role in the regulation of Vibrio parahaemolyticus surface behaviors, such as biofilm formation and swarming motility. The LuxO-OpaR QS pathway regulates swarming through control of the surface sensing system ScrABC and direct regulation of the lateral flagellar (laf) genes. I discovered that two closely related strains of V. parahaemolyticus, RIMD and RIMDORTH, display divergent swarming behaviors – RIMDORTH swarms while RIMD does not. This finding raises the question of what genomic difference(s) between these V. parahaemolyticus strains gives rise to this divergent behavior. I found there are no differences in QS or the ScrABC system between the two strains, and thus, I hypothesized that another mutation causes a shift in swarming regulation by affecting laf gene expression. I identified 17 genomic differences between the two strains and exchanged these variable regions between RIMD and RIMDORTH to screen for restoration or ablation of swarming behavior, respectively. Through exchange of these variable genomic regions, I identified clpX, a protease chaperone, as a novel gene possibly involved in swarming regulation. Further mechanistic experiments are required to confirm if clpX regulates swarming motility and to determine the pathway through which regulation occurs.