Viscosity-dependent swimming patterns assist Aliivibrio fischeri for symbiont partner finding

Bacteria employ diverse swimming patterns for chemotaxis, influenced by factors including flagellar arrangements, motor rotation, flagellar filament configurations, and polymorphism. Understanding the chemotactic strategy of Aliivibrio fischeri in locating a squid partner is paramount for comprehending this highly species-specific symbiosis. In this study, we applied three-dimensional swimming tracking and real-time visualization of lophotrichous flagellar configurations. These techniques unveiled viscosity-dependent transitions in swimming patterns, shifting from push-pull to push-wrap modes. Notably, our research also revealed synchronized flagellar switching and polymorphic transformations during the wrap mode, significantly extending A. fischeri’s backward swimming duration and, consequently, its overall run time. This strategic adaptation allows A. fischeri to broaden its effective search range, particularly within high-viscosity environments like the squid light organ. In response to attractants, the synchronization rate is reduced to facilitate efficient short-range searching. These innovative chemotactic strategies ensure precise navigation for A. fischeri in locating and colonizing its symbiotic partner, the squid Euprymna scolopes .