To Move or Not to Move: When and How Bacteria Suppress Flagellar Motility.

Bacterial motility enables cells to migrate toward favourable environments and initiate surface colonisation. While motility can be lost through passive processes, such as shearing of filament, it frequently occurs as a tightly regulated response shaped by environmental and ecological conditions. Cessation of motility is often not only a passive consequence of environmental limitations but can also represent a tightly regulated and adaptive strategy that promotes bacterial survival, persistence and biofilm development. Stopping motility allows the bacterial cells to redirect energy and metabolic resources toward essential processes, including extracellular matrix production and stress tolerance. This transition facilitates niche adaptation through protective biofilm communities which enhance bacterial stability under environmental stressors such as nutrient limitation, antimicrobial agents and host immune defences. Collectively, motility cessation represents a regulated shift to protective and communal lifestyles, with implications for bacterial ecology and pathogenesis. Studies have shown that bacteria use diverse mechanisms and signals for flagellar suppression, highlighting the importance of motility regulation in bacterial adaptation to changing environments. In this review, we highlight various mechanisms governing motility cessation and discuss the functional and environmental reasons that suppress motility across bacterial species.