Characterization of the flagellar biosynthesis regulatory gene flbD in Azospirillum brasilense

A flagellar gene cluster fragment including flbD of Azospirillum brasilense was cloned and sequenced. The flbD mutant strain was found to be nonmotile -losing both polar and lateral flagella (Fla(-)Laf(-)). Motility and flagel la were regained by complementation with plasmid-borne multicopy flbD, but altered with larger swarming circle and fewer lateral flagella on the semis olid plate. This result indicated that FlbD plays an important role in the regulation of both polar and lateral flagellar biosynthesis in A. brasilens e.