In Rhodobacter sphaeroides , a well studied case, motors alternate between turning and not turning. When the motor stops, the flagellum coils up very tightly, and the cells tumble until motor starts again. Spirochetes are well adapted to swim in viscous liquids. Mechanism not known, but appears to use proton gradient. Unusual sulfonolipids found in some gliding bacteria, such as Cytophaga sp.
Some gliding bacteria can move at rates that resemble swimming.
Both gliding and swimming bacteria can exhibit specific, tactic responses. Bacteria move in response to a change in nutrient concentration, not to the absolute concentration level. Hence, cells must adapt to prevailing conditions as a function of time. When phosphorylated, CheY can interact with FliM of the basal body motors to promote CW rotation and hence promote tumbling . Attractant binding to MCPs causes conformational change in MCP protein that is transmitted to the signalling domain in cytoplasm.