Biodeterioration of Microplastics by Bacteria Isolated from Mangrove Sediment

Abstract

As a kind of ubiquitous emerging pollutant, microplastics (MPs) are persistent in the environment and have a large impact on the ecosystem. Fortunately, some microorganisms in the natural environment can degrade these persistent MPs without creating secondary pollution. In this study, 11 different MPs were selected as carbon sources to screen the microorganisms for degradable MPs and explore the possible mechanism of degradation. After repeated domestication, a relatively stable microbial community was obtained after approximately 30 days later. At this time, the biomass of the medium ranged from 88 to 699 mg/L. The growth of bacteria with different MPs ranged from 0.030 to 0.090 optical density (OD) 600 of the first generation to 0.009–0.081 OD 600 of the third generation. The weight loss method was used to determine the biodegradation ratios of different MPs. The mass losses of polyhydroxybutyrate (PHB), polyethylene (PE), and polyhydroxyalkanoate (PHA) were relatively large, at 13.4%, 13.0%, and 12.7%, respectively; these figures for polyvinyl chloride (PVC) and polystyrene (PS) were relatively slight, 8.90% and 9.10%, respectively. The degradation half-life (t1/2) of 11 kinds of MPs ranges from 67 to 116 days. Among the mixed strains, Pseudomonas sp., Pandoraea sp., and Dyella sp. grew well. The possible degradation mechanism is that such microbial aggregates can adhere to the surface of MPs and form complex biofilms, secrete extracellular and intracellular enzymes, etc., break the hydrolyzable chemical bonds or ends of molecular chains by attacking the plastic molecular chains, and produce monomers, dimers, and other oligomers, leading to the reduction of the molecular weight of the plastic itself.

Characterization of an extremophile bacterial acid phosphatase derived from metagenomics analysis

“…The kinetic parameters determined for FS6 indicate that the enzyme is more efficient with potential physiological substrates than with artificial ones. This phenomenon has been observed in various hydrolases of fungal origin (Daddaoua et al., 2023 ) and enzymes that attack plastic monomers (Lai et al., 2023 ; Lear et al., 2021 ; Ren & Ni, 2023 ). However, the results with FS6 contrast with those obtained with another acid phosphatase extremozyme from Thermus thermophilus that exhibit the opposite behaviour (Tham et al., 2010 ).…”

High-throughput analysis using 16S rRNA sequencing of bacterial communities associated in selected mangrove species from Bayug Island, Iligan City, Philippines

“…In this process, microorganisms can transform contaminants into less harmful substances, influencing biogeochemical cycles (Cabral et al 2013;Dixit et al 2015;Brar et al 2017). Bacteria isolated from mangrove sediment have been shown to degrade persistent pollutants (Ren and Ni 2023); therefore, identifying and assessing microorganisms capable of degrading these pollutants is highly beneficial for bioremediation efforts and restoring natural ecosystems. This is particularly important for breaking down and transforming compounds like plastic polymers (Auta et al 2017).…”

“…For example, polypropylene (PP) can be degraded by microorganisms such as Rhizopus arrhizus A.Fisch., Vibrio, and Pseudomonas sp. (Raghul et al 2014;Ren and Ni 2023). Bacillus sp.…”

“…Bacillus sp. can degrade polyethylene (PE), and bacteria like Klebsiella, Citrobacter, and a species of the genus Pandoraea can degrade polystyrene (PS) (Venkatesh et al 2021;Cai et al 2023;Ren and Ni 2023). These functional bacterial communities within ecosystems enhance the organisms' survival rates (Thatoi et al 2013).…”