Effect of pH on Biohydrogen Production in Green Alga Tetraspora sp. CU2551

Abstract

The green alga Tetraspora sp. CU2551 has previously been identified as a hydrogen producing organism. With the promising potential in a high H2 production yield, we further studied the enhancement of the H2 production capacity by a substrate-level control to the key enzyme, Hydrogenase. This enzyme catalyzes the formation of biohydrogen gas from protons and electrons. Here, we investigated the effect of pH on the production rate which directly affected the flow of proton flux to the hydrogenase enzyme. The result revealed that pH of culture TAP medium was simply controlled by the use of HCl/NaOH solution over the pH range of 6.5 - 9.0 without any effect on the growth of algal cells. The H2 production was observed in all ranges of our focusing pH with comparable to the control condition (pH 7.0 of TAP medium). In our best condition, an increase of the H2 yield about 24% was found in cells cultivated in TAP medium adjusted the pH to 6.5 compared to the control condition. Our finding confirms the successful biohydrogen production enhancement by a substrate-level control for the key hydrogenase enzyme.