College of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China.
College of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China; Engineering Research Center of Agricultural Microbiology Technology, Ministry of Education & Heilongjiang Provincial Key Laboratory of Plant Genetic Engineering and Biological Fermentation Engineering for Cold Region & Key Laboratory of Microbiology, Department of Bioengineering, College of Heilongjiang Province & School of Life Sciences, Heilongjiang University, Harbin, 150080, PR China.
Environ Pollut. 2024 Sep 1;356:124346. doi: 10.1016/j.envpol.2024.124346. Epub 2024 Jun 7.
Triclocarban (TCC) and its metabolite, 3,4-dichloroaniline (DCA), are classified as emerging organic contaminants (EOCs). Significant concerns arise from water and soil contamination with TCC and its metabolites. These concerns are especially pronounced at high concentrations of up to approximately 20 mg/kg dry weight, as observed in wastewater treatment plants (WWTPs). Here, a TCC-degrading co-culture system comprising Rhodococcus rhodochrous BX2 and Pseudomonas sp. LY-1 was utilized to degrade TCC (14.5 mg/L) by 85.9% in 7 days, showing improved degradation efficiency compared with monocultures. A combination of high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), genome sequencing, transcriptomic analysis, and quantitative reverse transcription-PCR (qRT-PCR) was performed. Meanwhile, through the combination of further experiments involving heterologous expression and gene knockout, we proposed three TCC metabolic pathways and identified four key genes (tccG, tccS, phB, phL) involved in the TCC degradation process. Moreover, we revealed the internal labor division patterns and connections in the co-culture system, indicating that TCC hydrolysis products were exchanged between co-cultured strains. Additionally, mutualistic cooperation between BX2 and LY-1 enhances TCC degradation efficiency. Finally, phytotoxicity assays confirmed a significant reduction in the plant toxicity of TCC following synergistic degradation by two strains. The in-depth understanding of the TCC biotransformation mechanisms and microbial interactions provides useful information for elucidating the mechanism of the collaborative biodegradation of various contaminants.
三氯卡班（TCC）及其代谢物 3,4-二氯苯胺（DCA）被归类为新兴有机污染物（EOCs）。TCC 和其代谢物对水和土壤的污染引起了人们的高度关注。在污水处理厂（WWTPs）中，TCC 和其代谢物的浓度高达约 20mg/kg 干重，这种情况尤其令人担忧。在这里，利用包含 Rhodococcus rhodochrous BX2 和 Pseudomonas sp. LY-1 的 TCC 降解共培养系统在 7 天内将 TCC（14.5mg/L）降解了 85.9%，与单培养相比，显示出了更高的降解效率。采用高效液相色谱-串联质谱（HPLC-MS/MS）、基因组测序、转录组分析和定量逆转录聚合酶链式反应（qRT-PCR）进行了联合分析。同时，通过进一步的异源表达和基因敲除实验的组合，我们提出了三种 TCC 代谢途径，并鉴定了参与 TCC 降解过程的四个关键基因（tccG、tccS、phB、phL）。此外，我们揭示了共培养系统内部的分工模式和联系，表明 TCC 水解产物在共培养菌株之间进行了交换。此外，BX2 和 LY-1 之间的互利合作提高了 TCC 的降解效率。最后，植物毒性试验证实，两种菌株协同降解后 TCC 的植物毒性显著降低。深入了解 TCC 的生物转化机制和微生物相互作用为阐明各种污染物协同生物降解的机制提供了有用的信息。
