Abstract：
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.
摘要：
三氯卡班(TCC)及其代谢产物,3,4-二氯苯胺(DCA),被归类为新兴有机污染物(EOCs)。由于TCC及其代谢物的水和土壤污染引起了重大关注。这些问题在高达约20mg/kg干重的高浓度下尤其明显。如在污水处理厂(WWTP)中观察到的那样。这里,降解TCC的共培养系统,其包含杜氏红球菌BX2和假单胞菌属。LY-1在7天内降解TCC（14.5mg/L）85.9％，与单一培养物相比，降解效率提高。高效液相色谱-串联质谱联用(HPLC-MS/MS),基因组测序，转录组学分析，并进行定量逆转录-PCR(qRT-PCR)。同时,通过涉及异源表达和基因敲除的进一步实验相结合，我们提出了三种TCC代谢途径，并鉴定了四个关键基因(tccG，tccS,phB,phL)参与TCC降解过程。此外，我们揭示了合作文化系统中的内部分工模式和联系，表明TCC水解产物在共培养菌株之间交换。此外,BX2和LY-1之间的相互合作提高了TCC降解效率。最后,植物毒性试验证实，在两种菌株协同降解后，TCC的植物毒性显着降低。对TCC生物转化机制和微生物相互作用的深入了解为阐明各种污染物的协同生物降解机制提供了有用的信息。
