With the globally rising usage of plastics, including polyethylene terephthalate (PET), the environmental risk that disposal of waste plastics to landfills and discharge of microplastics to the marine environment pose have also increased. For example, observation of animal ingestion of fragmented waste plastics (micro- and nano-plastics) has driven awareness for the need of proper environmental risk assessment. In evaluating the biodegradability of PET-derived byproducts and their precursors, most work has focused on hydrolytic enzymes and aerobic organisms that possess such genes, but only few reports on biodegradation in the absence of oxygen (i.e., anaerobic) are available. Here, to elucidate the fate of PET-derived materials under anaerobic environments, a sludge-derived microbial community was cultured with bis(2-hydroxyethyl) terephthalate (BHET) as a model substrate for byproducts of PET degradation and dimethyl terephthalate (DMT) as a potential environmental pollutant discharged from the PET manufacturing process. Metagenome- and metabolome-informed microbiome analyses identified anaerobic BHET and DMT degradation pathways, uncultured organisms affiliated with Spirochaetota and Negativicutes predominant in the BHET-fed cultures, and Methanomethylovorans and Treponema_G predominant in the DMT-fed cultures. Metagenomic analyses newly identified three BHET-degrading and two DMT-degrading enzymes from the genomes of Spirochaeota. In addition, the Negativicutes in the BHET enrichment cultures possessed genes for acetogenically metabolizing EG and/or ethanol. Overall, this study successfully established anaerobic BHET- and DMT-degrading microbial consortia and newly proposed these degradation mechanisms under anaerobic conditions. This study indicated that the cultivation, microbiome, and metabolome analyses can be powerful tools for elucidating consortia capable of degrading plastics-associated waste compounds and the relevant metabolic mechanisms.

随着包括聚对苯二甲酸乙二醇酯 (PET) 在内的塑料在全球范围内的使用量不断增加，将废塑料填埋和向海洋环境排放微塑料所带来的环境风险也在增加。例如，观察动物摄入碎片化的废塑料（微塑料和纳米塑料），促使人们意识到需要进行适当的环境风险评估。在评估 PET 衍生副产物及其前体的生物降解性时，大多数工作都集中在水解酶和具有此类基因的需氧生物上，但很少有关于在无氧条件下生物降解的报道（即, 厌氧) 可用。在这里，为了阐明厌氧环境下 PET 衍生材料的命运，用对苯二甲酸双 (2-羟乙基) 酯 (BHET) 作为 PET 降解副产物的模型底物和对苯二甲酸二甲酯 (DMT) 作为模型底物培养了污泥衍生的微生物群落。 PET制造过程中排放的潜在环境污染物。基于宏基因组和代谢组的微生物组分析确定了厌氧 BHET 和 DMT 降解途径、未培养的与螺旋体有关的生物体和在 BHET 喂养的培养物中占优势的阴性菌，以及甲烷甲基食人动物和 Treponema_G 在 DMT 喂养的文化中占主导地位。宏基因组分析新发现了螺旋体基因组中的三种 BHET 降解酶和两种 DMT 降解酶。此外，BHET 富集培养物中的阴性菌具有产乙酸代谢 EG 和/或乙醇的基因。总体而言，本研究成功地建立了厌氧 BHET 和 DMT 降解微生物群落，并新提出了厌氧条件下的这些降解机制。该研究表明，培养、微生物组和代谢组分析可以成为阐明能够降解塑料相关废物的联合体及其相关代谢机制的有力工具。