Reversal of flagellar rotation in monotrichous and peritrichous bacteria: generation of changes in direction

Reversal of flagellar rotation can explain both the "backing up" of monoflagellated Pseudomonas citronellolis and the tumbling of multiflagellated Salmonella typhimurium. Reversals occur spontaneously and can be induced by negative gradients of attractant and by high-intensity light.