Effect of Exogenous Substrates on Hydrogen Photoproduction by a Marine Cyanobacterium, Synechococcus sp. Miami BG 043511

Abstract

In this study, the effects of exogenous substrates on hydrogen production were examined using synchronously grown cells of Synechococcus sp. strain Miami 043511. When synchronously grown cells were used, enhancement of hydrogen production was observed by the addition of pyruvate only after about a 20-h incubation period. This enhancement, however, was not so large as observed in batch-grown, late-log phase cells. The period when the enhancement began coincided with the period when substantial cessation in hydrogen production in control cells was observed. This can be interpreted to mean that the utilization of exogenous substrate occurs only when an endogenously available carbohydrate is depleted. Although glucose and pyruvate were good substrates for hydrogen production in late-log to stationary-phase, batch-grown cells, substantial enhancement was not observed in synchronously grown cells. Pyruvate but not glucose was effective to some extent in prolonging hydrogen production in synchronously grown cells. This enhancement of hydrogen production was ascribed to prolonged activity of nitrogenase due to the addition of pyruvate.