Biodegradation of Typical Plastics: From Microbial Diversity to Metabolic Mechanisms

Abstract

Plastic production has increased dramatically, leading to accumulated plastic waste in the ocean. Marine plastics can be broken down into microplastics (<5 mm) by sunlight, machinery, and pressure. The accumulation of microplastics in organisms and the release of plastic additives can adversely affect the health of marine organisms. Biodegradation is one way to address plastic pollution in an environmentally friendly manner. Marine microorganisms can be more adapted to fluctuating environmental conditions such as salinity, temperature, pH, and pressure compared with terrestrial microorganisms, providing new opportunities to address plastic pollution. Pseudomonadota (Proteobacteria), Bacteroidota (Bacteroidetes), Bacillota (Firmicutes), and Cyanobacteria were frequently found on plastic biofilms and may degrade plastics. Currently, diverse plastic-degrading bacteria are being isolated from marine environments such as offshore and deep oceanic waters, especially Pseudomonas spp. Bacillus spp. Alcanivoras spp. and Actinomycetes. Some marine fungi and algae have also been revealed as plastic degraders. In this review, we focused on the advances in plastic biodegradation by marine microorganisms and their enzymes (esterase, cutinase, laccase, etc.) involved in the process of biodegradation of polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP) and highlighted the need to study plastic biodegradation in the deep sea.

Bottlenecks in biobased approaches to plastic degradation

“…This alteration of the C-C bonds is hypothesized to proceed in a manner analogous to the process of catabolizing long-chain alkanes which may include the hydroxylation of the C–C bonds resulting in alcohols 56 . This initial hydroxylation may be accompanied by further oxidation 9 , 57 . Oxygenation changes the resulting polymer traits and deviates from a pure polymer-to-polymer circularization scheme.…”

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

“…PET esterases, PET cutinases and PET depolymerases are hydrolytic enzymes that are able to break the ester bonds of biological molecules, like suberin and cutin, and due to their unspecificity, it turns out that they can break those of PET as well. On the other hand, PETases are hydrolytic enzymes more specific to PET [80,81]. Due to the Despite the advantages provided by PET, it also presents the serious drawback of what to do with it after its useful life.…”

“…PET esterases, PET cutinases and PET depolymerases are hydrolytic enzymes that are able to break the ester bonds of biological molecules, like suberin and cutin, and due to their unspecificity, it turns out that they can break those of PET as well. On the other hand, PETases are hydrolytic enzymes more specific to PET [80,81]. Due to the specificity, there are small differences between the different types of enzymes, such as PET cutinases, which can hydrolyze the ester bonds of aliphatic and aromatic molecules, while PETases can only hydrolyze bonds of aromatic molecules [54,65,69].…”

Progress and Prospects of Microplastic Biodegradation Processes and Mechanisms: A Bibliometric Analysis

“…In other words, surface modification improves the wettability, fastness, dyeing, and pilling resistance of microplastics and ultimately the hydrophilicity of plastics. The surface area-to-volume ratio plays an important role in the degradation process; the higher or lower this ratio is, the more easily the polymer can degrade compared to fiber or film [55][56][57].…”