Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province, China.
Sci Rep. 2016 Jul 20;6:29675. doi: 10.1038/srep29675.
The highly recalcitrant 1H-1,2,4-triazole (TZ) is widely used in the synthesis of agricultural pesticide and considered to be an environmental pollutant. In this study, a novel strain NJUST26 capable of utilizing TZ as the sole carbon and nitrogen source, was isolated from TZ-contaminated soil, and identified as Shinella sp. The biodegradation assays suggested that optimal temperature and pH for TZ degradation by NJUST26 were 30 °C and 6-7, respectively. With the increase of initial TZ concentration from 100 to 320 mg L(-1), the maximum volumetric degradation rate increased from 29.06 to 82.96 mg L(-1) d(-1), indicating high tolerance of NJUST26 towards TZ. TZ biodegradation could be accelerated through the addition of glucose, sucrose and yeast extract at relatively low dosage. The main metabolites, including 1,2-dihydro-3H-1,2,4-triazol-3-one (DHTO), semicarbazide and urea were identified. Based on these results, biodegradation pathway of TZ by NJUST26 was proposed, i.e., TZ was firstly oxidized to DHTO, and then the cleavage of DHTO ring occurred to generate N-hydrazonomethyl-formamide, which could be further degraded to biodegradable semicarbazide and urea.
高度稳定的 1H-1,2,4-三唑（TZ）广泛应用于农业农药的合成，被认为是一种环境污染物。本研究从 TZ 污染土壤中分离到一株能够利用 TZ 作为唯一碳源和氮源的新型菌株 NJUST26，并鉴定为鞘氨醇单胞菌属。生物降解实验表明，NJUST26 降解 TZ 的最佳温度和 pH 值分别为 30°C 和 6-7。随着初始 TZ 浓度从 100 增加到 320mg/L，最大容积降解速率从 29.06 增加到 82.96mg/L/d，表明 NJUST26 对 TZ 具有较高的耐受性。通过在相对较低的剂量下添加葡萄糖、蔗糖和酵母提取物，可以加速 TZ 的生物降解。鉴定出的主要代谢物包括 1,2-二氢-3H-1,2,4-三唑-3-酮（DHTO）、氨基脲和尿素。基于这些结果，提出了 NJUST26 降解 TZ 的生物降解途径，即 TZ 首先被氧化为 DHTO，然后 DHTO 环发生裂解生成 N-羟甲基甲脒，可进一步降解为可生物降解的氨基脲和尿素。
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