Fungal solid-state fermentation of food waste for biohydrogen production by dark fermentation.

The dark fermentation process was evaluated for biohydrogen production from food waste through fungal solid-state fermentation (SSF). Three fungal cultures (one strain of Aspergillus tubingensis and two strains of Meyerozyma caribbica) were compared, being A. tubingensis the best hydrolyser culture for releasing soluble carbohydrates. The biochemical hydrogen potential of food waste hydrolysate (FWH) at different substrate-inoculum ratios obtained a lower hydrogen yield than untreated food waste (RFW). The highest hydrogen yield value corresponded to treatments RFW-20 and RFW-30 with 77.0 ± 2.6 and 76.9 ± 1.4 mL H 2 normalized by per gram volatile solid added (NmL H 2 /gVS added), respectively. The microbial community of food waste was analysed, being detected lactic-acid bacteria genera as Latilactobacillus and Leuconostoc. The presence of actively growing bacteria during the SSF could explain the lowest hydrogen yield (20.1–36.0 NmL H 2 /gVS added) in the FWH treatment due to the substrate competition between lactic-acid bacteria and hydrogen-producing bacteria, where the lactic-acid bacteria were favoured by their faster growth rate. • The fungal solid-state fermentation of food waste using A. tubingensis increased the released carbohydrates. • The presence of indigenous lactic-acid bacteria from food waste could affect H 2 production. • Food waste hydrolysate with A. tubingensis obtained a lower H 2 yield than control. • The use of fungal solid-state fermentation decreased the lag phase of the dark fermentation process. [ABSTRACT FROM AUTHOR]