Effects of some physical factors on flagellation and swarming of Vibrio alginolyticus

Abstract

Vibrio alginolyticus strains, recently isolated from Dutch coastal sea water, had cells with a single, sheathed, polar flagellum with a wavelength of c. 1.5 μm and a thickness of c. 25 nm, when grown in liquid medium. On agar media, lateral flagella were predominant with a wavelength of c. 0.9 μm; their thickness was c. 15 nm. Unsheathed polar flagella with a wavelength of c. 1.5 μm and a thickness of 15 nm were sometimes observed. A distinction is proposed between the terms “variable flagellation” and “mixed flagellation”. In agar cultures, incubated at 40°C or above, the number of lateral flagella was strongly reduced. Polar flagella were less susceptible to higher temperatures. On media with 0.5% agar or less at 25°C, lateral flagella were rarely found; when grown on membrane filters with a supply of liquid medium, the vibrios produced lateral flagella. The results indicate that peritrichous flagellation is induced by a solid support of sufficient consistency, not necessarily containing agar. For swarming on agar media, presence of lateral flagella was necessary but not sufficient. Swarming may also depend on the brand of agar used. Implications for taxonomical studies are discussed. The hypothesis is introduced that the induction of peritrichous flagellation by a solid substrate is of ecological importance: the lateral flagella would hold the cells on particulate matter, providing nutrients in sufficient concentrations.