Hydrogen peroxide inhibits the growth of cyanobacteria

H2O2 at concentrations of 10(-5)-10(-4) M suppresses phototrophic growth of Anacystis nidulans and Anabaena variabilis in dialysis culture. The growth of the cyanobacteria resumed after a long adaptation period. In batch cult ures, the growth of A. nidulans and A. variabilis was suppressed after one- time addition of 10(-2) and 10(-3)-10(-2) M H2O2, respectively. Inducing in tracellular H2O2 formation by adding methylviologen, vitamin K-3, or phenaz ine methosulfate suppresses the growth of both cyanobacteria. The catalase inhibitor salicylic acid suppresses the growth of A. nidulans and A. variab ilis at a concentration of 5.10(-3) M. The data suggest an inhibitory effec t of H2O2 on the growth of the cyanobacteria. H2O2 is unlikely to serve as an electron donor during photosynthesis.