Limosilactobacillus Regulating Microbial Communities to Overcome the Hydrolysis Bottleneck with Efficient One-Step Co-Production of H 2 and CH 4 .

The efficient co-production of H 2 and CH 4 via anaerobic digestion (AD) requires separate stages, as it cannot yet be achieved in one step. Lactic acid bacteria (LAB) (Limosilactobacillus) release H 2 and acetate by enhancing hydrolysis, potentially increasing CH 4 production with simultaneous H 2 accumulation. This study investigated the enhanced effect of one-step co-production of H 2 and CH 4 in AD by LAB and elucidated its enhancement mechanisms. The results showed that 236.3 times increase in H 2 production and 7.1 times increase in CH 4 production are achieved, resulting in profits of 469.39 USD. Model substrates lignocellulosic straw, sodium acetate, and H 2 confirmes LAB work on the hydrolysis stage and subsequent sustainable volatile fatty acid production during the first 6 days of AD. In this stage, the enrichment of Limosilactobacillus carrying bglB and xynB, the glycolysis pathway, and the high activity of protease, acetate kinase, and [FeFe] hydrogenase, jointly achieved rapid acetate and H 2 accumulation, driving hydrogenotrophic methanogenesis dominated. From day 7 to 24, with enriched Methanosarcina, and increased methenyltetrahydromethanopterin hydrogenase activity, continuously produced acetate led to the mainly acetoclastic methanogenesis shift from hydrogenotrophic methanogenesis. The power generation capacity of LAB-enhanced AD is 333.33 times that of China's 24,000 m 3 biogas plant.