Progress in microbiology for fermentative hydrogen production from organic wastes

Dark fermentative hydrogen production from organic wastes can achieve dual benefits of clean energy generation and waste utilization, which offers the best prospects for a biohydrogen production process with high environmental benefits. Biohydrogen production system is a complex biological process, which is affected by many factors, including operational conditions (e.g. temperature, pH), substrate type, reactor design etc., and depends on the microbial type, retention time, activity, productivity and end products. Among these influencing factors the hydrogen-producing microorganisms play a vital role. Great efforts have been made to enhance the hydrogen production efficiency from the perspective of microbiology. In this review, the microbiology, biochemistry and enzymology for biological hydrogen production were briefly summarized and analyzed. The recent progress in microbiology for hydrogen production through dark fermentation was reviewed, including microorganisms, biochemistry, enzymology, microbial modification and the identification of the microbial community structure. Metabolic pathways can be modified by metabolic engineering, thus enhancing the biological hydrogen production through overcoming limiting factors for hydrogen production in various systems by increasing the flow of electrons to hydrogen-producing pathways, increasing substrate utilization, and engineering more efficient and/or oxygen-resistant hydrogen-evolving enzymes. Finally, concluding remarks and perspectives are given.