Flagellum-independent surface migration of Vibrio cholerae and Escherichiacoli

Surface translocation has been described in a large variety of microorganis ms, including some gramnegative enteric bacteria, sere, we describe the nov el observation of the flagellum-independent migration of Vibrio cholerae an d Escherichia coli on semisolid surfaces with remarkable speeds. Important aspects of this motility are the form of inoculation, the medium compositio n, and the use of agarose rather than agar, Mutations in several known regu latory or surface structure proteins, such as ToxR, ToxT, TCP, and PilA, di d not affect migration, whereas a defect tn lipopolysaccharide biosynthesis prevented translocation, We propose that the observed surface migration is an active process, since heat, protease, or chloramphenicol treatments of the cells have strong negative effects on this phenotype, Furthermore, seve ral V. cholerae strains strongly expressing the hemagglutinin/protease but not their isogenic hap-negative mutants, lacked the ability of surface moti lity, and the treatment of migrating strains with culture supernatants from hap strains but not hap-null strains prevented surface translocation,.