Engineered bacteria for PET and polyethylene degradation: A review

The increasing concentration of polyethylene terephthalate (PET) and polyethylene (PE) in the environment, along with their resistance to biodegradation, poses a serious threat to the environment and living organisms. Emerging trends in recombinant DNA technology and synthetic biology, such as genetically modified bacteria, have revealed novel strategies for the biodegradation of plastics. This review focuses on the capability of genetically engineered bacteria, such as CRISPR-edited strains, to break down PET and PE. Genetically modified bacteria offer an alternative approach to traditional recycling techniques for more effective management of PET and PE waste. Significantly, new life-cycle assessments (LCAs) show that enzymatic PET recycling can cut greenhouse gas emissions by 30–40 % when compared to the manufacturing of virgin PET; nonetheless, issues with the cost of enzyme synthesis and the energy requirements for pretreatment still exist. Regulatory approval for the discharge or confinement of modified microorganisms and their incorporation into frameworks for the circular economy is also necessary for the sustainability of such strategies. This review emphasizes various bacterial strains, enzymatic modifications, and the challenges of recent strategies, including the efficiency of different enzymes and sustainable biocatalyst development, while also suggesting future research strategies. • Engineered bacteria enhance PET and polyethylene degradation beyond natural processes. • PET degradation needs PETase & MHETase from I. sakaiensis plus oxidative pathways. • Bacterial plastic degradation faces limits due to low enzyme efficiency & scaling issues.