Comparison of hydrogen and volatile fatty acid production by Bacillus cereus, Enterococcus faecalis and Enterobacter aerogenes singly, in co-cultures or in the bioaugmentation of microbial consortium from sugarcane vinasse

Abstract

Abstract Vinasse is a main residue of ethanol production, generated daily in large scale in Brazil. The anaerobic processing of vinasse can be a sustainable alternative for generation of fuel and co-products. The production of hydrogen and VFAs from different concentrations of sugarcane vinasse were evaluated by Bacillus cereus, Enterobacter aerogenes and Enterococcus faecalis singly, as cocultures, in bioaugmentation and by microbial consortium. The increase of vinasse concentration positively affected the production of hydrogen. B. cereus alone showed the higher hydrogen production using undiluted vinasse (100%) (85.41 mmol H 2 L−1) and higher yield (5.40 mmolH2 g−1COD), for both vinasse concentration (50, 70 and 100%). The performance of co-culture (B. cereus + E. aerogenes + E. faecalis) was similar (2.45 mmol H 2 g−1 COD) to the microbial consortium (2.59 mmol H 2 g−1 COD). The bioaugmentation of microbial consortium with B. cereus, E. aerogenes and E. faecalis separately did not increase hydrogen production. Total VFAs yield increased in the 30% vinasse concentration. The main metabolite produced was butyric acid for singly microorganisms and microbial consortium. Whereas acetic acid was predominant in both co-culture and bioaugmentation assays. This study showed the potential of isolated strain B. cereus in the production of hydrogen and VFAs, using vinasse as a substrate, giving a sustainable destination for the residue of high polluting risk.