The operation of bioelectrochemical systems (BESs) relies on the ability of microbes to export electrons outside of their cells. However, microorganisms are not evolutionary conceived to power BESs as most of the redox processes occur within. In this study, a low cost strategy equivalent to the one used to improve hydrogen production is employed to divert electrons from the metabolism to an electrode. Varying the ratio of nitrogen to carbon concentration (0, 0.20 and 0.54) determines what fraction of the electron flux is directed towards biosynthesis, biohydrogen generation and extracellular electron transfer. The ratio of 0.54 produced a higher specific growth rate while the ratio of 0.20 resulted in combined higher maximum specific hydrogen production and exoelectrogenic activity, translating into a maximum power density of 2.39 ± 0.13 mW m-2 in a novel hybrid hydrogen-photosynthetic microbial fuel cell. The current work sets a framework for the optimisation of R. palustris for bioenergy recovery.
Keywords: Biohydrogen generation; Exoelectrogenic activity; Nitrogen regime; Photosynthetic microbial fuel cell (photoMFC); Rhodopseudomonas palustris.
Copyright © 2019. Published by Elsevier Ltd.