Abstract
An alga-lytic bacterium, Pseudomonas KA6, was isolated from Lake Kasumigaura by a double-layer method. the filtrate of Pseudomonas KA6 culture lysed Phormidium tenue promptly. It was found that the growth of P. tenue is controlled by the addition of the filtrate 5 % and more. The lysis of P. tenue occurred efficiently at 25-35°C and pH 7-9. the cell of P. tenue in the stationary and endogenous phases was lysed promptly compared with that of P. tenue in the logarithmic phase. The filtrate lysed Oscillatoria sp. and Anabaena planktonica immediately as well as P. tenue; however, the filtrate lysed Microcystis aeruginosa slowly, and did not lyse green algae and diatoms. It was suggested that lytic compounds in the filtrate of KA6 culture affect only cyanobacteria in a water environment.
