John Garner

PLA from PolySciTech used in investigation of enzymatic degradation of plastics

Blog Post created by John Garner on Oct 10, 2018

2018 PLA environmental degradation.jpg

An environmental hazard which has been growing over the years is the accumulation of plastic waste. Since conventional plastics, such as polyethylene and polypropylene, do not degrade easily, they remain in the ocean and other places for a long time. Recently, researchers from University of Toronto utilized a series of PLA’s (AP005, AP004, AP047) from PolySciTech ( to investigate the role of environmental enzymes in breaking down PLA, a potential replacement for other plastics which can biodegrade under environmental conditions. This research holds promise for improved degradability of polyesters to reduce environmental burdens. Read more: Hajighasemi, Mahbod, Anatoli Tchigvintsev, Boguslaw P. Nocek, Robert Flick, Ana Popovic, Tran Hai, Anna N. Khusnutdinova et al. "Screening and characterization of novel polyesterases from environmental metagenomes with high hydrolytic activity against synthetic polyesters." Environmental Science & Technology (2018).


  “Abstract: The continuous growth of global plastics production, including polyesters, has resulted in increasing plastic pollution and subsequent negative environmental impacts. Therefore, enzyme-catalyzed depolymerization of synthetic polyesters as a plastics recycling approach has become a focus of research. In this study, we screened over 200 purified uncharacterized hydrolases from environmental metagenomes and sequenced microbial genomes and identified at least 10 proteins with high hydrolytic activity against synthetic polyesters. These include the metagenomic esterases MGS0156 and GEN0105, which hydrolyzed polylactic acid (PLA), polycaprolactone, as well as bis(benzoyloxyethyl)-terephthalate. With solid PLA as a substrate, both enzymes produced a mixture of lactic acid monomers, dimers, and higher oligomers as products. The crystal structure of MGS0156 was determined at 1.95 Å resolution and revealed a modified α/β hydrolase fold, with a lid domain and highly hydrophobic active site. Mutational studies of MGS0156 identified the residues critical for hydrolytic activity against both polyester and monoester substrates, with two-times higher polyesterase activity in the MGS0156 L169A mutant protein. Thus, our work identified novel, highly active polyesterases in environmental metagenomes and provided molecular insights into their activity, thereby augmenting our understanding of enzymatic polyester hydrolysis.”