Microbial ecology of a lactate-driven dark fermentation process producing hydrogen under carbohydrate-limiting conditions

摘要: Abstract Despite the high prevalence of lactic acid bacteria in dark fermentation (DF) processes, their ecological role is not yet completely elucidated, preventing systematic use as “helpers” for hydrogen production. The aim this study was to investigate microbial community structure a lactate-driven DF process that successfully produced under carbohydrate-limiting conditions using tequila vinasse substrate. Microbial responses stepwise decreases hydraulic retention time (HRT) from 24 4 h were assessed by Illumina MiSeq sequencing. HRTs above 12 h and below 6 h led lower production rate (HPR; 0.2–3.3 L/L-d) stability (HPR variations within 25–65%), which associated with presence Acetobacter lovaniensis, Clostridium luticellari, Blautia coccoides, abundance propionate lactate. Interestingly, transient unsteady-to-steady state occurred at an HRT 12 h, where species richness evenness decreased remarkably. Accordingly, between 12 resulted higher HPRs up 11.7 ± 0.7 L/L-d HPR less than 10%, closely matched dominance sp., butyrate acetate main aqueous products. Overall, results indicate successfulness exploiting ‘unwanted’ LAB proliferation through processes requires enrichment lactate-consuming hydrogen-producing bacteria, entails selection proper biocatalysts operating conditions/strategies such operation reactors low HRTs.