Regulation of nitrogen source for enhanced photobiological H2 production by co-culture of Chlamydomonas reinhardtii and Mesorhizobium sangaii

Abstract

Nitrogen compounds play an important role in the growth and hydrogen production of microalgae. Here, we report how different nitrogen compounds regulate biomass production and hydrogen accumulation in a Chlamydomonas reinhardtii and Mesorhizobium sangaii co-cultivation system. Our results show that the addition of three different nitrogen compounds can all increase the biomass and hydrogen production of the co-cultured microalgae. Among them, 3 g/L NaNO2 shows the best efficacy with the maximum H2 production reaching 226.98 μmol/mg chl, which is 5.2 times higher than that of the pure algae group. The hydrogenase activity, respiration rate, chlorophyll content, and starch accumulation of the algae were also increased in the presence of different nitrogen compounds, which would be corresponding to the enhanced hydrogen production. And sustainable hydrogen production can be achieved by intermittent supplement of nitrogen compounds into the microalgae-bacteria co-culture system. Our study provides a promising way to enhance and prolong the biomass and hydrogen production of microalgae-bacteria co-culture systems by the regulation of nitrogen compounds.