Project description:Food waste is a major source of environmental pollution, as its landfills attribute to greenhouse gas emissions. This study developed a robust upcycling bioprocess that converts food waste into lactic acid through autochthonous fermentation and further produces biodegradable polymer polyhydroxybutyrate (PHB). Food can be stored without affecting its bioconversion to lactic acid, making it feasible for industrial application. Mapping autochthonous microbiota in the food waste fermentation before and after storage revealed lactic-acid-producing microorganisms dominate during the indigenous fermentation. Furthermore, through global transcriptomic and gene set enrichment analyses, it was discovered that coupling lactic acid as carbon source with ammonium sulfate as nitrogen source in Cupriavidus necator culture upregulates pathways, including PHB biosynthesis, CO2 fixation, carbon metabolism, pyruvate metabolism, and energy metabolism compared to pairing with ammonium nitrate. There was ∼90 % PHB content in the biomass. Overall, the study provides crucial insights into establishing a bioprocess for food waste repurposing.
Project description:Industrial anaerobic digestion (AD) represents a relevant energy source beyond today’s fossil fuels, wherein organic matter is recycled to methane gas via an intricate and complex microbial food web. Despite its potential, anaerobic reactors often undergo process instability over time, mainly caused by substrate composition perturbations, making the system unreliable for stable energy production. To ensure the reliability of AD technologies, it is crucial to identify microbial- and system responses to better understand the effect of such perturbations and ultimately detect signatures indicative of process failure . Here, we investigate the effect of microalgal organic loading rate (OLR) on the fermentation products profile, microbiome dynamics, and disruption/recovery of major microbial metabolisms. Reactors subjected to low- and high-OLR disturbances were operated and monitored for fermentation products and biogas production over time, while microbial responses were investigated via 16S rRNA gene amplicon data, shotgun metagenomics and metagenome-centric metaproteomics.