Effect of phenazine against rice leaf blight bacterium, and its biochemical mechanism

(1) Employing the chemically defined medium containing L-cystine, in which the growth environmental condition seems to be similar to that in the host plant at least as for the growth limiting factor, phenazine was found as a peculiar bacteriostatic agent having the wide range of partial growth inhibitory activity against Xanthomonas oryzae.(2) Regarding rice plant pot tests against the leaf blight disease in our phytotrone, phenazine showed a fairy high inhibitory value, dose at 200ppm was ca. 93% and dose at 150ppm was ca. 83%.(3) One aspect on the action mechanism of phenazine against the bacterium was elucidated, that is, phenazine seemed to be incorporated into the respiratory system of the bacterium and it formed the respiratory regulating system to suppress the rate of the respiration.