[Interaction of cyanobacteria cells with methyl viologen]

Oxygen absorption instead of its evolution is induced in cell suspensions of the cyanobacteria Anacystis nidulans and Anabaena variabilis in the presence of methylviologen, an autoxidable electron acceptor, and triphenyltetrazolium chloride which is irreversibly reduced in the cells. The process occurs without addition of exogenous donors and does not depend on DCMU. Dichlorophenolindophenol and ascorbate do not stimulate the absorption. The blue colour of reduced methylviologen was not observed even after argon had been bubbled through a cuvette with the reaction mixture. Cell decoloration and lysis were found upon long contact with methylviologen. Elevated concentrations of DCMU also caused oxygen absorption in the light. Apparently, it is possible to induce oxidation of endogenous donors in the cells of the above cyanobacteria in the presence of methyl-viologen.