Biohydrogen production from cheese whey in UASB and packed bed reactors: Impact of microbial interactions on productivity

Raw cheese whey has an endogenous microbial community that interacts with hydrogen producers in ways not yet fully understood. This work evaluates the hydrogen productivity and microbial interactions between lactic acid bacteria and hydrogen producers. The hydrogen production performance was studied in a UASB and a packed bed reactor at different organic loading rates. Performance results evidence that hydrogen productivity was more efficient in UASB than in the packed bed and was strongly influenced by the loading rates, determining the microbial community developed. A network analysis showed that Megasphaera was the primary H 2 producer in both configurations. Members with the most microbial interactions were related to the hydrolysis of protein and chitosan, the production of vitamins, and the consumption of volatile fatty acids for caproate production. Caproiciproducens present many positive interactions. This study provided new insights into the importance of bacterial interactions and opened new strategies for enhancing biohydrogen productivity. • H 2 productivity was influenced by the OLR, determining the microbial community. • Due to the process operation, H 2 productivity was more efficient with UASB than PBR. • Hydrolysis and production of vitamins were relevant microbial interactions. • The H 2 producer Megasphaera established a higher number of interactions. • Caproiciproducens positively interact with several taxa despite their low abundance.