Escalating Photobiological Hydrogen Production Using Engineered Selenium Nanoparticles

This study assessed the effect of selenium nanoparticles (SeNPs), a metalloid-based semiconducting NP, on the growth of the photosynthetic bacterium Rhodopseudomonas palustris and its production of photofermentative hydrogen (H-2) metabolized from acetate. The addition of 0.1 mg/L SeNPs enhanced the growth of R. palustris and increased H-2 production by 7.34% in the stationary phase. Furthermore, the decoration of SeNPs with chitosan and vitamin E improved stability and increased H-2 production by 20.48 and 34.43%, respectively, in growing R. palustris. Nitrogen-starved, nongrowing R. palustris could increase the H-2 yield by fully oxidizing acetate. The decoration of SeNPs with chitosan and vitamin E resulted in a 66.42 and 77.94% increase in H-2 production of nongrowing R. palustris, with yields of 1.06 and 1.08 mol/mol acetate, respectively, which are comparable to reported yields metabolized from 6-carbon hexose. Finally, the study provided evidence that SeNPs augment H-2 production by facilitating electron transfer from photophosphorylation to the H-2-producing enzyme. Therefore, this study will enable the advanced optimization of photobiological H-2 production using engineered NPs.