A Gas-Vacuolate Phototrophic Bacterium Isolated from the Bacterial Plate of Lake Kaiike

抄録

A gas-vacuolate phototrophic bacterium was isolated from the bacterial plate at the mid-depth of Lake Kaiike using the medium of PFENNIG (1965) The bacterium was ovoid to short-rod (3 to 5 by 4 to 8 μm) in shape, and buoyant when it contained gas vacuoles. It formed a violet suspension and a pinkish flotation on the top of the medium, and at depletion of H2S entered the stationary phase. Gas vacuoles were easily collapsed when the bacterial suspension was centrifuged (1000 g, 15 min.). The bacterium was motile and similar to Lamprocystis roseopersicina. In early November 1984, this bacterium was predominant in the bacterial plate. At the same time, a considerable amount of irregular-shaped violet slime composed of the bacterium covered the entire surface of the lake.