Plaque Formation by Algicidal Saprospira sp. on a Lawn of Chaetoceros ceratosporum.

Abstract

The bacterial strains belonging to the genus Saprospira were isolated from sea water samples in Kagoshima Bay and shrimp aquaculture ponds by using of the mixed culture with marine diatoms and double layer agar techniques. A Saprospira strain SS90-1 formed craterlike plaques on a lawn of Chaetoceros ceratosporum, which enlarged unlimitedly in the way of concentric cycles during an incubation period under illumination. The plaque formation by Saprospira SS90-1 was repressed with antibiotics including penicillin G, ampicillin, streptomycin, erythromycin, and tetracycline. Saprospira spp. have been reported to be isolated from decomposing plant debris or soil in terrestrial habitats, and also from decaying algae, sand or mud in aquatic environments.1)