The Selective Inhibitory Activity of a Fusaricidin Derivative on a Bloom-Forming Cyanobacterium, Microcystis sp

Fusaricidin analogs, produced by , were tested for selective control of a major bloom-forming cyanobacterium, sp. Fusaricidin (A and B mixtures) and four analogs were isolated from E681 and investigated for their inhibition of cyanobacterial cell growth. Among the four fusaricidin analogs, fraction 915 Da (designated as Fus901) showed growth inhibition activity for but not for and . Microcystin concentration decreased up to 70% and its content per cell also decreased over 50% after 3 days. Fusaricidin exhibited growth inhibition against Gram-positive bacteria but Fus901 did not. Molecular weights of fusaricidin A and B were 883 Da and 897 Da, whereas that of Fus901 was 915 Da. Structure analysis by a ring-opening method revealed a linear form for Fus901. Expression of the gene related to oxidative stress was increased 2.1-fold by Fus901 and that of decreased up to 40%. These results indicate that Fus901 exerts oxidative stress against . Thus, Fus901 can be used as a selective cyanobactericide without disturbing the ecological system and could help in decreasing the microcystin concentration.