Effects of some inhibitors and carbon sources on acetylene reduction and hydrogen production of isolated heterocysts of Anabaena sp. (strain CA)

Abstract

Metabolically active heterocysts isolated from wild-type Anabaena sp. strain CA showed high rates of light dependent acetylene reduction and H₂ evolution. Fructose and erythrose significantly stimulated nitrogenase activity but not H₂ evolution. DCMU and cyanide were not effective. DBMIB significantly inhibited both nitrogenase and nitrogenase-catalysed H₂ evolution. This inhibition was overcome by a catalytic amount of TMPD. These data suggest that in the isolated heterocysts all electrons, irrespective of source, must pass through the plastoquinone pool before reducing ferredoxin, which in turn can reduce dinitrogen to ammonia.