Expression of the structural gene, laf1, encoding the flagellin of the lateral flagella in Azospirillum brasilense Sp7

The induction of the lateral flagella of Azospirillum brasilense Sp7 was studied by using a translational fusion between the laf1 promoter and gusA. The fusion was induced when cells were grown on solid media but not when they were grown in broth. The fusion was also induced by incubation of liquid-grown cells with an anti-polar flagellum polyclonal antiserum. Hindrance of polar-flagellum rotation is suggested to be the signal for this induction.