Light stimulation strategy for promoting bio-hydrogen production: Microbial community, metabolic pathway and long-term application

Light stimulation strategy for promoting bio-H-2 production was firstly investigated with incandescent light. The light condition controlled by photon number (N-R, 0.63 x 10(4)-6.25 x 10(4) mu mol/(day.L)) was applied to stimulate H-2 fermentation process. The optimal N-R of 3.75 x 10(4) mu mol/(day.L) contributed to 1.4 folds H-2 yield of the dark reactor and promoted efficient H-2 producing pathway (acetate and nicotinamide adenine dinucleotide pathway) with increased microbial activities.& nbsp;Furthermore, the effect of light stimulation on microbial community was identified. Fervidobacterium, Coprothermobacter and OPB95 were the dominant genera that could be activated by light stimulation for promoting acetate pathway and contribute to higher H-2 production. Moreover, long-term operation showed more stable and higher H-2 production of light stimulated bioreactor than the dark one, which resulted from the light stimulated metabolic pathway, increased sludge conductance and promoted microbial immobilization. This novel light stimulation strategy is promising for future application on promoting bio-H-2 production.

Automated summary

A light stimulation strategy was investigated to promote bio-H-2 production. The optimal light condition increased H-2 yield and promoted efficient H-2 producing pathway. The microbial community was also affected by light stimulation. Long-term operation showed higher and more stable H-2 production in the light stimulated bioreactor.