Engineering whole-cell catalysts to use plastic waste as a feedstock

The extensive production, durability, and waste mismanagement of plastic polymers have led to a highly concerning environmental problem. Recycling methods aim to reduce the amount of plastic pollution, and among them, biological processes have emerged as an interesting alternative for the management of plastic waste that is difficult to collect or can not be recycled by other methods. While there has been significant progress in the field, in particular related to the enzymatic hydrolysis of polyesters, most biological methods rely on the use of enzymes in vitro, using collected plastics. In this review, we explore the status of technologies using whole-cell catalysts that could be used for in vivo upcycling of plastic waste - with plastic becoming a microbial feedstock - and for the development of biodegradation strategies in relevant environments. We have identified a number of barriers related to polymer bioavailability, enzyme activity and secretion, and the use of strains and microbial communities that need to be overcome to materialize a much-needed solution to plastic pollution.