Isolation and characterization of gliding motility mutants of Cytophaga columnaris

1. A number of motility mutants derived from the gliding bacterium Cytophaga columnaris were obtained by allowing motile cells to spread from an inoculated area on an agar plate and then removing cells from the center of the inoculated area. This procedure was repeated ten times. Suspensions of cells resulting from this selection procedure were spread on agar plates, and colonies which lacked the spreading edges typical of wild-type cells were picked for further study. 2. Mutants were examined in slide cultures, on agar plates under various conditions of incubation, and by electron microscopy. 3. Two classes of motility mutants were isolated. Cells of one class are only nonmotile under certain conditions of incubation, whereas cells of the second class are nonmotile under all conditions tested. One mutant of this second class lacks a system of fibrils which is present in surface layers of cells of the parent strain.