Microbial community dynamics and hydrogen production in tequila vinasse dark fermentation Targeted loci environmental
This study elucidates the impact of vinasse detoxification and hydraulic retention time (HRT) on bacterial diversity and its consequent effect on hydrogen production during dark fermentation. Using a continuous stirred tank reactor (CSTR), we investigated how operational parameters shape microbial ecology, dictating process stability and hydrogen yield from tequila vinasse. Fermenting detoxified vinasse led to lower bacterial richness compared with raw vinasse and resulted in erratic, low hydrogen production. In contrast, raw vinasse supported stable hydrogen productivity dominated by Clostridium. Increasing the HRT from 6 to 18 h triggered a profound microbial shift, favoring lactic acid bacteria (Sporolactobacillus) and Ethanoligenens over Clostridium, with a drastic drop in hydrogen yield. Notably, even after resetting the HRT to 6 h, Sporolactobacillus remained dominant and hydrogen productivity only marginally recovered, revealing a clear hysteresis effect. The 16S rRNA gene (V3-V4 region) amplicon sequencing was used to track bacterial community succession across different operational stages. This study demonstrates that operational parameters in dark fermentation directly shape the microbial ecology, which in turn dictates process stability and hydrogen yield. The findings provide critical insights for microbial resource management in industrial-scale biohydrogen production from agro-industrial waste.