Hydrogen-supported nitrogenase activity in two cyanobacteria

The effects of hydrogen gas on nitrogenase activity of nitrogen-fixing cyanobacteria Aulosira fertilissima and Chlorogloeopsis fritschii were studied. Addition of as little as 10% hydrogen either in air, N<SUB>2</SUB>, or N<SUB>2+</SUB>CO<SUB>2</SUB> markedly stimulated acetylene reduction. It has been shown that hydrogen can act as an alternate source both under reductant-saturating and reductant-deficient conditions. The results indicate the presence of a strong oxyhydrogen reaction in both species