International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok, Thailand; Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Bangkok, Thailand.
Center of Excellence in Microbial Technology for Marine Pollution Treatment (MiTMaPT), Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
Chemosphere. 2023 Jan;310:136730. doi: 10.1016/j.chemosphere.2022.136730. Epub 2022 Oct 6.
Di-(2-ethylhexyl) phthalate (DEHP) is an extensively used and toxic phthalate plasticizer that is widely reported in marine environments. Degradation of DEHP by bacteria from several environments have been studied, but little is known about marine sediment bacteria that can degrade DEHP and other phthalate plasticizers. Therefore, in this study, we enriched a bacterial consortium C10 that can degrade four phthalate plasticizers of varying alkyl chain lengths (DEHP, dibutyl phthalate, diethyl phthalate, and dimethyl phthalate) from marine sediment. The major bacterial genera in C10 during degradation of the phthalate plasticizers were Glutamicibacter, Ochrobactrum, Pseudomonas, Bacillus, Stenotrophomonas, and Methylophaga. Growth of C10 on DEHP intermediates (mono-ethylhexyl phthalate, 2-ethylhexanol, phthalic acid, and protocatechuic acid) was studied and these intermediates enhanced the Brevibacterium, Ochrobactrum, Achromobacter, Bacillus, Sporosarcina, and Microbacterium populations. Using a network-based approach, we predicted that Bacillus, Stenotrophomonas, and Microbacterium interacted cooperatively and were the main degraders of phthalate plasticizers. Through selective isolation techniques, we obtained twenty isolates belonging to Bacillus, Microbacterium, Sporosarcina, Micrococcus, Ochrobactrum, Stenotrophomonas, Alcaligenes, and Cytobacillus. The best DEHP-degraders were Stenotrophomonas acidaminiphila OR13, Microbacterium esteraromaticum OR16, Sporosarcina sp. OR19, and Cytobacillus firmus OR20 (83.68%, 59.1%, 43.4%, and 40.6% degradation of 100 mg/L DEHP in 8 d), which agrees with the prediction of key degraders. This is the first report of DEHP degradation by all four bacteria and, thus, our findings reveal as yet unknown PAE-degradation capabilities of marine sediment bacteria. This study provides insights into how bacterial communities adapt to degrade or resist the toxicities of different PAEs and demonstrates a simple approach for the prediction and isolation of potential pollutant degraders from complex and dynamic bacterial communities.
邻苯二甲酸二（2-乙基己基）酯（DEHP）是一种广泛使用且有毒的邻苯二甲酸酯类增塑剂，广泛存在于海洋环境中。已经研究了来自不同环境的细菌对 DEHP 的降解，但对于能够降解 DEHP 和其他邻苯二甲酸酯类增塑剂的海洋沉积物细菌知之甚少。因此，在这项研究中，我们从海洋沉积物中富集了一个能够降解四种不同支链长度的邻苯二甲酸酯类增塑剂（DEHP、邻苯二甲酸二丁酯、邻苯二甲酸二乙酯和邻苯二甲酸二甲酯）的细菌混合体 C10。在降解邻苯二甲酸酯类增塑剂的过程中，C10 中的主要细菌属为谷氨酸菌属、食酸菌属、假单胞菌属、芽孢杆菌属、寡养单胞菌属和噬甲基菌属。研究了 C10 在 DEHP 中间体（单乙基己基邻苯二甲酸酯、2-乙基己醇、邻苯二甲酸和原儿茶酸）上的生长情况，这些中间体增强了 Brevibacterium、食酸菌属、不动杆菌属、芽孢杆菌属、球形芽孢杆菌属和微杆菌属的种群。通过基于网络的方法，我们预测芽孢杆菌属、寡养单胞菌属和微杆菌属相互合作，是邻苯二甲酸酯类增塑剂的主要降解菌。通过选择性分离技术，我们获得了二十株属于芽孢杆菌属、微杆菌属、球形芽孢杆菌属、微球菌属、食酸菌属、寡养单胞菌属、产碱菌属和纤维单胞菌属的分离株。DEHP 降解效果最好的菌株是恶臭假单胞菌 OR13、不动杆菌属 OR16、球形芽孢杆菌 OR19 和纤维单胞菌属 OR20（在 8 d 内分别降解 100 mg/L DEHP 的 83.68%、59.1%、43.4%和 40.6%），这与关键降解菌的预测结果一致。这是首次报道这四种细菌都能降解 DEHP，因此我们的研究结果揭示了海洋沉积物细菌对 PAE 降解的未知能力。本研究为了解细菌群落如何适应降解或抵抗不同 PAE 的毒性提供了新的见解，并展示了一种从复杂和动态的细菌群落中预测和分离潜在污染物降解菌的简单方法。
