A phase variant of Azospirillum lipoferum lacks a polar flagellum and constitutively expresses mechanosensing lateral flagella

Flagellation of a nonswimming variant of the mixed flagellated bacterium Az ospirillum lipoferum 4B was characterized by electron microscopy, and polyc lonal antibodies were raised against polar and lateral flagellins. The vari ant cells lacked a polar flagellum due to a defect in flagellin synthesis a nd constitutively expressed lateral flagella. The variant cells were able t o respond to conditions that restricted the rotation of lateral flagella by producing more lateral flagella, suggesting that the lateral flagella, as well as the polar flagellum, are mechanosensing.