Fundamentals of Polymer Biodegradation Mechanisms

Microorganisms are capable of degrading many polymers. The general process involves the secretion of enzymes that fragment the polymer into small oligomers, which can then be taken up and metabolized by the microorganisms. Recently, many have proposed that biological processes can be used for plastic recycling. However, such processes provide a route for waste destruction, where the polymer is degraded to CO 2 and H 2 O, and are typically viewed as an environmental safeguard. Some biodegradation efforts, however, enable the complete depolymerization of certain plastics that can be subsequently reformulated with properties comparable to that of the virgin polymer. Polyesters have great potential in this area. Other plastics such as hydrocarbons, which are overrepresented in the waste landscape, are inherently recalcitrant to biological degradation and would require a pretreatment step to prime the molecular chains for microbial degradation and assimilation. This chapter reviews our current understanding of microbial polymer degradation and discusses the potential and challenges associated with using biology for plastic waste disposal and recycling.