Exploring the biodegradation of PET in mangrove soil and its intermediates by enriched bacterial consortia

The biodegradation of Polyethylene terephthalate (PET) is important due to the environmental impact of plastic waste. This study investigates the degradation of PET films in soil microcosms, with and without mangrove plants, and with mangrove plants bioaugmented with a bacterial consortium (Bacillus sp.- GPB12 and Enterococcus sp.- WTP31B-5) while following the evolution of soil microcosm microbiome. The ability of bacterial consortia retrieved from soil microcosms of each tested condition to degrade PET intermediates - bis(2-hydroxyethyl) terephthalate (BHET), terephthalic acid (TPA), and monoethylene glycol (MEG) was also assessed. In the microcosms' assays with mangrove plants, variations in functional groups and surface morphology detected by FTIR and SEM analysis indicated PET degradation. Soil microcosms microbiome evolved differently according to the conditions imposed, with dominance of phylum Proteobacteria in all final microcosms. After 270 days, bacterial consortia retrieved from all soil microcosms revealed to be able to completely degrade TPA within three days. MEG degradation reached ca. 84% using the consortium retrieved from the microcosm with bioaugmented mangrove plants. BHETdegradation was ca. 96% with the consortium obtained from the microcosm with non-bioaugmented mangrove plants. These intermediates are key molecules in PET degradation pathways; thus, their degradation is an indicator of biodegradation potential. To the best of authors' knowledge, this is the first report on biodegradation of PET, BHET, TPA, and MEG by microbial community from mangrove soil, providing insights into key taxa involved in PET degradation. These findings can pave a way to develop bioremediation strategies and more efficient waste management solutions.