Analysis of the carbon metabolism of Rhodopseudomonas palustris for biohydrogen production

Abstract

Hydrogen can be produced renewably and sustainably by the purple non-sulfur bacterium Rhodopseudomonas palustris from sucrose. To improve hydrogen production, detailed insight is needed, which can be obtained by studying the coupling of carbon fluxes with the light utilization apparatus and the hydrogen producing enzymes. In this study, the flux balance analysis approach was used to construct a model of the central carbon metabolism of this organism and solve the resulting network for a chosen objective function. The model was able to closely reproduce key qualitative and quantitative aspects of an independent experimental study. Further insight was obtained by additional case studies. Specifically, it was found that extreme light intensities resulted in the decrease of hydrogen production, that hydrogen production could be possible even when no light is provided, and a mix of sucrose and an organic acid could improve hydrogen production, which can be explained and supported by prior work on this organism. Further investigation is necessary to investigate the connections between metabolic network components, such the antagonistic relationship between hydrogen and polyhydroxybutyrate, which is a reserve product of this microorganism.