Microbial Bioresource for Plastic‐Degrading Enzymes

Abstract

Conventional methods of removing plastic waste cause adverse environmental effects, which have sparked a huge interest in microbes as environmentally friendly alternatives. Microbes play a vital role in the self-cleaning ability of our planet, acting as microreactors, and have evolved over time to keep up with the ever-changing flux of xenobiotics and contaminants including plastic waste. These mini bioreactors include actinomycetes, algae, bacteria, and fungi, which along with their enzymes, are the key players in the plastic degradation process. These microbial enzymes have been demonstrated to partially degrade recalcitrant fossil-based plastic polymers such as polypropylene, polyethylene, polyethylene terephthalate, polystyrene, and polyvinyl chloride. In addition, they have also been shown to significantly break down the less resistant biobased plastics such as polylactic acid, polyhydroxyalkanoates, poly-3-hydroxybutyrate, polyhydroxyvalerate, and polyhydroxyhexanoate. Consequently, this chapter will examine how microorganisms and their enzymes can be utilized as bioresource for plastic degradation. It delves into the general mechanism of microbial plastic degradation centered on biofragmentation, biodeterioration, mineralization, and assimilation. In addition to the basic conventional methods used to identify and isolate plastic-degrading microbes and their enzymes, advanced biochemical techniques are also discussed for improving the efficiency of these bioreactors, such as metagenomics, protein engineering, and recombinant technology. This chapter also identifies critical knowledge gaps and future research directions in the effective utilization of microbes as bioresources for plastic degradation.