Indigenous microbial systems for the production of green chemicals via anaerobic fermentation

Conventional anaerobic fermentation (AF) for agroindustrial waste (AGW) valorization into added-value metabolites is typically inoculated using anaerobic sludge from anaerobic digesters. This inoculum contains methanogens, which are the main metabolite-consumers to produce biogas. In this investigation, the use of indigenous microbial community present in the AGW was evaluated as an alternative inoculum since it lacks of methanogens. Self-AF (lacking external inoculum) showed high bioconversion efficiencies to metabolites (>63%) regardless of process pH. Nevertheless, pH mediated a metabolite profile oscillation. Whereas a pH of 4.6 maximized the lactic acid and ethanol production due to the lactic acid bacteria prevalence, a pH of 6 promoted a microbiome specialized in carboxylates production with Clostridiales (69.8%) and Bifidobacteriaceae (29.2%) as key bacteria. This work demonstrated the feasibility of performing AF in the absence of external inoculum. Moreover, the wide bacterial metabolisms present in indigenous microbiota revealed its capability of maximizing product portfolio using self-AF.