Hydrogen Evolution by Nitrogen-Fixing Anabaena cylindrica Cultures

Abstract
Actively growing, nitrogen-fixing cultures of the blue-green alga Anabaena cylindrica can simultaneously evolve hydrogen and oxygen frolni water and light. Hydrogen evolution was strongly inhibited by N2 but only slightly by CO or O2, characteristics of the nitrogenase reaction in the heterocysts of Anabaena cylindrica. We suggest that this reaction has potential use in solar energy conversion.