The “CUPRO” project focuses on the sustainable and microbial production of a novel bioplastic and the valorisation of the spent microbial protein in feed starting from 2nd generation (2G) feedstocks. The growing concern about the environmental impact of current fossil-based plastics as well as the need for sustainable feeding solutions are the key drivers for this project. Within CUPRO, full consumption of the carbohydrates within 2G feedstocks will be enabled and optimised with advanced engineering tools. This will result in a platform strain that can use various carbon feedstocks. In parallel, the microbial host will also be trained to produce the bioplastic of choice with high efficiency. An optimized multi-stage fermentation process will be developed and a tailored purification strategy will be designed and fine-tuned. The latter will result in a high-purity bioplastic and in a microbial protein which can then be used in feed applications. Overall, CUPRO will enable the sustainable production of a fully biodegradable bioplastic while also valorising its ‘waste’ protein stream in feeding applications. The CUPRO project thus contributes to the transition towards a carbon-neutral economy while providing solutions for the protein transition.