Hydrogen production by a green alga, <i>Chlamydomonas reinhardtii</i>, in an alternating light/dark cycle

Abstract

The evolution of H(2) in the dark period of a light/dark cycle by a green alga, Chlamydomonas reinhardtii, was studied with the aim of developing a two/stage biophotolysis system. The algal cells accumulated starch during the growth period in light. When these cells were incubated microaerobically in the dark, hydrogenase activity was induced was induced without an appreciable lag time and therapy H(2) evolution was observed for several hours to more than 10 h, depending upon the amount of added O(2). The cells harvested in the midlogarithmic growth phase were the most efficient in production of H(2) in the dark. H(2) evolution was highly dependent on temperature, but rather incentive to pH values from 5-9. Based on these observations, altering production of O(2) and H(2) was demonstrated repeatedly in a light/dark cycle.