Reverse and flick: Hybrid locomotion in bacteria

Abstract

Many bacteria are motile. They use one or more helical flagella as propellers, rotating them like the corkscrew on a wine bottle opener. Despite the limited morphological repertoire of the propulsive system, radically different movement strategies have evolved, likely reflecting the diversity of physicochemical conditions among bacterial habitats. In PNAS, Xie et al. (1) report on a newly discovered mechanism for turning used by Vibrio alginolyticus, an inhabitant of the coastal ocean: These monotrichous (“single-haired”) bacteria change direction with a “flick” of their flagellum. Intriguingly, Xie et al. (1) show that less can be more when it comes to bacterial flagella: With its single flagellum, V. alginolyticus outperforms the multiflagellated Escherichia coli in climbing nutrient gradients (“chemotaxis”), suggesting that the flick is part of an advanced chemotaxis system.