Different aspects of bacterial polyethylene terephthalate biodegradation

Abstract Background Polyethylene terephthalate (PET) is a kind of synthetic plastic used in the production of single-use disposable materials. Widespread use of PET leads to its accumulation in the environment. Incineration, landfilling, and recycling are some solutions to this problem. However, these methods have limitations, such as secondary toxic wastes. Main body of the abstract Here, biodegradation can be a biological solution to the PET pollution problem, which takes advantage of the metabolic diversity of living organisms for pollutant removal. Among different microorganisms, bacteria are efficient PET degraders that can use PET as the sole source of carbon and energy. Bacterial biodegradation of PET occurs through some metabolic pathways, converting it into terephthalic acid (TPA) and ethylene glycol (EG). Incomplete hydrolysis products, such as mono-(2-hydroxyethyl) terephthalate (MHET) and bis-(2-hydroxyethyl) terephthalate (BHET), appear in this process as well. These intermediates are produced via the action of different enzymes, among which PET hydrolases play a key role. Some factors such as pH, enzyme specificity, temperature, and PET polymer crystallinity affect bacterial PET biodegradation. Short conclusion Despite being economical and eco-friendly, PET biodegradation faces limitations such as low enzymatic stability, low expression level of enzymes involved in this process, and enzyme inhibition by PET hydrolysis intermediates. These problems may be solved through enzyme engineering, genetic engineering of PET-biodegrading bacteria, and construction of artificial PET-degrading bacterial consortia. If these problems are solved, biodegradation will be an attractive solution for the problem of PET pollution. The present investigation aims at different aspects of bacterial PET biodegradation, such as its mechanisms, metabolic pathways, advantages, and limitations.