Engineering Adipic acid Metabolism in a Thermotolerant Bacterium Cupriavidus cauae PHS1 for Sustainable Plastic Upcycling

Abstract

Plastic pollution has become an urgent problem in contemporary society. The global use of plastics is expected to increase from 464 Mt in 2020 up to 884 Mt in 2050, with up to 4725 Mt of plastics accumulated in stock in 2050. Despite this pressing issue, only about 9% of plastic waste has been recycled worldwide. One tempting solution to this crisis is upcycling plastics into products with engineered microorganisms. Adipic acid and other medium-chainlength dicarboxylates are key components of many plastics, including polyamides and polyesters. While microbial degradation of adipic acid and other mcl-dicarboxylates was characterized in Acinetobacter baylyi ADP1, only few strains can degrade adipic acid. In this respect, this thermotolerant bacterium shows an advantage due to its growth on adipic acid as a sole carbon source. However, this strain exhibited a prolonged lag phase when grown on adipic acid as the sole carbon source. To address this limitation, this study explores strategies to improve adipic acid metabolism in this strain. Through the use of genetic tools, specific genetic changes linked to enhanced cell growth on adipic acid are identified and evaluated. This study will provide a powerful thermotolerant platform strain for metabolism of complex plastic hydrolysates.