In this study, a lactate-type fermentation entailing the consumption of lactate and acetate (lactate-acetate pathway) is proposed to deal with lactic acid bacteria (LAB) inhibition during the production of biohydrogen (bioH2) from tequila vinasse. The effects of total solids content, substrate concentration, nutrient formulation and inoculum addition on bioH2 production performance were investigated. Batch experiments were performed in a 3-L completely mixed reactor at 35 °C and pH 6.5-5.8. The lactate-acetate pathway mediated consistent bioH2 production which was influenced by inoculum addition followed by substrate concentration, nutrient formulation and solids content. Maximum bioH2 production rate (225 NmL/L-h) and yield (124 NmL/g VSadded) were achieved by removing suspended solids and enhancing nutrient content, respectively. Illumina sequencing-based analysis revealed a dominance of Clostridium in the inoculum, which together with LAB and acetic acid bacteria shaped a keystone cluster for avoiding LAB inhibition while ensuring consistent bioH2 production performance.
Keywords: Dark fermentation; Gompertz model; Hydrogen-producing bacteria; Lactic acid bacteria; Monod model.
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