Abstract
Pseudomonas fluorescens HYK0210-SK09 (SK09) has the algicidal activity against Stephanodiscus hantzschii that frequently forms bloom in winter season. In this study, the growth possibility of SK09 was investigated in two microcosm experiments using Stephanodiscus hantzschii culture. We monitored the abundance of SK09 using the Pseudomonas specific probe in tyramide signal amplification ? fluorescence in situ hybridization. In the first experiment, we inoculated SK09 into Stephanodiscus culture. Stephanodiscus cell density decreased to the half within two days. Simultaneously, both SK09 and other bacterial cell densities increased to about 3 times higher densities. In the second experiment, we inoculated Stephanodiscus to enriched-filtered river water and monitored cell densities of Stephanodiscus, SK09, other bacteria and flagellates. Inoculation of SK09 cells on 8 days caused rapid decrease in Stephanodiscus cell density to the half within 2 days. SK09 and other bacterial cell densities increased in 1.5 times on 1 day after the inoculation, and then their cell densities rapidly decreased probably due to grazing by flagellates. Flagellates cell density increased in 5 times after the inoculation. These results demonstrate that SK09 can grow using their algicidal activity on Stephanodiscus and that the algicidal activity of SK09 affect abundance of other bacteria and flagellates.
