An acid-tolerant Clostridium sp. BLY-1 strain with high biohydrogen production rate.

Screening and isolating acid-tolerant bacteria capable of efficient hydrogen production can mitigate the inhibitory effects on microbial activity caused by rapid pH drops during fermentation. In this study, we isolated an acid-tolerant and highly efficient hydrogen-producing bacterium, named Clostridium sp. BLY-1, from acidic soil. Compared to the model strain Clostridium pasteurianum DSM 525, BLY-1 demonstrates a faster growth rate and superior hydrogen production capabilities. At an initial pH of 4.0, BLY-1's hydrogen production is 7.5 times greater than that of DSM 525, and under optimal conditions (pH=5.0), BLY-1's hydrogen production rate is 42.13% higher than DSM 525. Genomic analysis revealed that BLY-1 possesses a complete CiaRH two-component system and several stress-resistance components absent in DSM 525, which enhance its growth and hydrogen production in acidic environments. These findings provide a novel avenue for boosting the hydrogen production capabilities of Clostridium strains, offering new resources for advancing the green hydrogen industry.

Batch fermentative hydrogen production by enriched mixed culture: Combination strategy and their microbial composition.

The effect of individual and combined mixed culture on dark fermentative hydrogen production performance was investigated. Mixed cultures from cow dung (C1), sewage sludge (C2), and pig slurry (C3) were enriched under strict anaerobic conditions at 37°C with glucose as the sole carbon source. Biochemical hydrogen production test in peptone-yeast-glucose (PYG) and basal medium was performed for individual mixed cultures (C1, C2 and C3) and their combinations (C1-C2, C2-C3, C1-C3 and C1-C2-C3) at a glucose concentration of 10 g/L, 37°C and initial pH 7. Maximum hydrogen yields (HY) of 2.0 and 1.86 [Formula: see text] by C2, and 1.98 and 1.95 mol(H2)/mol(glucose) by C2-C3 were obtained in PYG and basal medium, respectively. Butyrate and acetate were the major soluble metabolites produced by all the cultures, and the ratio of butyrate to acetate was ∼2 fold higher in basal medium than PYG medium, indicating strong influence of media formulation on glucose catabolism. The major hydrogen-producing bacterial strains, observed in all mixed cultures, belonged to Clostridium butyricum, C. saccharobutylicum, C. tertium and C. perfringens. The hydrogen production performance of the combined mixed culture (C2-C3) was further evaluated on beverage wastewater (10 g/L) at pH 7 and 37°C. The results showed an HY of 1.92 mol(H2)/mol(glucose-equivalent). Experimental evidence suggests that hydrogen fermentation by mixed culture combination could be a novel strategy to improve the HY from industrial wastewater.