Exploring PETase-like enzyme from shotgun metagenome and co-expressing Colicin E7 in Escherichia coli for effective PET degradation

Polyethylene terephthalate (PET) is the conventional plastic used for packaging but disposal of PET in the natural environment poses significant threats to the ecological system. In the biological process, the degradation of PET plastic using PET-degrading enzyme (PETase) has attracted scientific interest, thus increasing the exploration of PETase evolution. This study aims to exploit a new PETase from a greenhouse farm in Tainan, Taiwan. The in-silico approach of shotgun metagenomic analysis, enzyme structural prediction, molecular docking and simulations were applied, thus narrowing the cleft and identifying a potential PETase-like enzyme, denoted as F148. The heterologous expression of F148 in Escherichia coli strains was capable of breaking down PET into terephthalate monomer (TPA). Furthermore, the PET-degrading ability of F148 was optimized using the incorporation of MHETase and Colicin E7 via in vitro and in vivo digestion methods, respectively. The in vivo system served as a concise approach due to allowing simultaneous F148 secretion, thus achieving the highest TPA amount of 0.56 mg, equivalent to 11.2% weight loss of PET. This study not only contributes promising insights into the exploration of a distinctive gene but also successfully invents an efficient PETase using a one-step in vivo process in genetically modified E. coli.