Breakdown of polyethylene therepthalate microplastics under saltwater conditions using engineered Vibrio natriegens

Abstract

Poly(ethylene terephthalate) (PET) is a highly recyclable plastic that has been extensively used and manufactured. Like other plastics, PET resists natural degradation, thus accumulating in the environment. Several recycling strategies have been applied to PET, but these tend to result in downcycled products that eventually end up in landfills. This accumulation of landfilled PET waste contributes to the formation of microplastics, which pose a serious threat to marine life and ecosystems, and potentially to human health. To address this issue, our project leveraged synthetic biology to develop a whole‐cell biocatalyst capable of depolymerizing PET in seawater environments by using the fast‐growing, nonpathogenic, moderate halophile Vibrio natriegens. By leveraging a two‐enzyme system—comprising a chimera of IsPETase and IsMHETase from Ideonella sakaiensis—displayed on V. natriegens, we constructed whole‐cell catalysts that depolymerize PET and convert it into its monomers in salt‐containing media and at a temperature of 30°C.

Identification and expression of MarCE, a marine carboxylesterase with synthetic ester‐degrading activity

“…Petroleum‐based, non‐biodegradable synthetic plastics have an environmental half‐life that ranges from several to a few thousand years. Since PET plastic is employed in packaging and textiles due to its strength and physicochemical resistances, PET‐based materials are slow to degrade in nature, whether by microbial‐based or abiotic processes (Li, Menegatti, & Crook, 2023 ). The conversion of waste plastics into high‐purity monomers or value‐added products has gained much traction as a way to sustainably manage and circularize the life cycle of synthetic materials, with biocatalytic approaches of particular interest to enable depolymerization under mild reaction conditions (Lee et al., 2023 ).…”

Degradation of PET Plastics by Wastewater Bacteria Engineered via Conjugation

“…In this work, we demonstrated a proof-of-concept for genetically engineering bacteria from municipal wastewater in situ to degrade PET plastics by using a broad-host-range, conjugating plasmid carrying the FAST-PETase gene. Previous studies have focused on optimizing expression and secretion of PET-degrading enzymes in single species 44–46 , or employing naturally occurring and designer microbial communities to degrade PET plastics 14,15,47,48 . In contrast, we genetically engineered bacterial isolates from an environmental sample to degrade PET via expression of an engineered PETase that exhibits high activity at moderate temperatures.…”

Genetic Modifications in Bacteria for the Degradation of Synthetic Polymers: A Review

“…The estimate increases if its degradation is not accelerated by heat or solar radiation, reaching 2500 years or more. PET is so difficult to degrade due to its physicochemical properties, which make it resistant to decomposition by water and organic and inorganic compounds [73,76].…”

“…Another recent project using this technique appears in Li et al [73]. The researchers modified the non-pathogenic, moderate halophile Vibrio natriegens with a chimera of IsPETase and IsMHETase from I. sakaiensis, with the aim of degrading PET present in seawater.…”