Gut plastizyme: Systematic Review to identify gut microbiota enzymesproposed as plastic degradation resources

Rapid industrialization and anthropogenic activities have led to the widespread occurrence of emerging contaminants, such as plasticizers and microplastics. These pollutants are a global concern due to their persistence and ability to interfere with endocrine systems, potentially causing adverse ecological and health effects. This systematic review identifies plastic degradation enzyme capacities within the gut microbiome taxa, previously described for environmental microorganisms. A search term was conducted using the following keywords: “Biodegradation”, “Microbial degradation”, “xenobiotic metabolism”, “microbial degradation pathways”, “enzymes”, “laccase”, “monooxygenase”, “dioxygenase”, “dehydrogenase”, “Bisphenol A” (BPA), “Xenobiotics”, and “Endocrine disruptor”. Records were screened against inclusion criteria based on keywords detected in the titles and abstracts of original articles and experimental studies on the specific microbial degradation of BPA, in which specific enzymes, genes, or metabolic pathways were described. The analysis and presentation of the data obtained from the systematic review search were organized in accordance with the PRISMA 2020 flow diagram for a new systematic review. A summary of the microorganisms with BPA-degrading enzymes identified in in vitro studies was compiled, highlighting genera such as Lactobacillus, Enterococcus, Bacillus and Pseudomonas. Their key enzymatic mechanisms primarily involve the action of laccases, peroxidases, or cytochrome P450, which transform BPA into intermediates such as hydroquinone, 4-hidroxybenzoic acid, or 4-hidroxyacetophenone. It has been also described the homology of the first environmental plastizyme with the specific enzymatic repertoire (laccases, dioxygenases, and hydratases) of species taxonomically closest to the intestinal microbiota isolates, as determined by bioinformatic and molecular analyses of complete genomes (whole-genome sequencing, WGS). To extrapolate these results, a pilot complementary bioinformatic approach will be carried out with a reconstructed MAG (Metagenome-assambled Genome) from gut microbiota from a children cohort with a known level of BPA exposure to validate and describe the presence of “gut plastizyme” and specific “gut BPAzyme”.