Resource recovery from the anaerobic digestion of food waste is underpinned by cross-kingdom microbial activities

As the human population grows on the planet so does the generation of waste and particularly that of food waste. In order to tackle the world sustainability crisis, efforts to recover products from waste are critical. Here, we anaerobically recovered volatile fatty acids (VFAs) from food waste and analysed the microbial populations underpinning the process. An increased contribution of fungi relative to bacteria was observed throughout the reactor operation, with both kingdoms implicated into the main three steps of anaerobic digestion occurring within our systems: hydrolysis, acidogenesis and acetogenesis. Overall, Ascomycota, Proteobacteria and Firmicutes were found to drive the anaerobic digestion of food waste, with butyrate as the most abundant VFA likely produced by Clostridium using lactate as a precursor. Taken together we demonstrate that the generation of products of added-value from food waste results from cross-kingdoms microbial activities implicating fungi and bacteria.