Orthosulfamuron, a rice herbicide of the family pyrimidinyl sulfonylurea, causes ground water contamination for its moderate persistence and high water solubility. It may cause phytotoxicity and, thereby, affect the growth of succeeding crops. Keeping in view of the environmental safety, the interaction between orthosulfamuron and soil fungi was investigated. Ten different fungal species were found to survive in the soil containing orthosulfamuron at the level of 50 mg kg⁻¹. However, based on the previous research reports, Aspergillus niger was selected for the degradation study on orthosulfamuron in the sterilized soil. It exhibited concentration-depended degradation rate for orthosulfamuron, where the rate decreased with the increasing concentration of the herbicide. The degradation pattern of the herbicide followed the first-order rate kinetics for each applied concentration. The structural elucidation of the five degradation products by liquid chromatography-mass spectroscopic analysis indicated that the fungal strain could degrade the herbicide through various biochemical processes. The major degradation of the herbicide took place through the hydrolytic cleavage of sulfonylurea bridge and cleavage of N (urea bridge)–C (pyrimidinyl ring) bond. The rate and degradation pattern of orthosulfamuron found in the present study strongly imply the presence of a recognition mechanism for the substrate and a consequent metabolic response system in the A. niger strain isolated from the agricultural soil.

邻磺嘧磺隆是嘧啶基磺酰脲类的水稻除草剂，因其持久性中等和水溶性高而引起地下水污染。它可能会引起植物毒性，从而影响后续作物的生长。考虑到环境安全性，研究了邻磺磺隆与土壤真菌之间的相互作用。发现在含有邻磺氨磺隆的土壤中，有10种不同的真菌物种以50 mg kg ^-1的水平存活。但是，根据以前的研究报告，黑曲霉选择在消毒土壤中对原磺酰胺进行降解研究。它表现出浓度依赖于原磺酰胺的降解速率，其中降解速率随除草剂浓度的增加而降低。除草剂的降解方式遵循每种施用浓度的一级速率动力学。通过液相色谱-质谱分析对这五种降解产物进行结构分析，结果表明该真菌菌株可以通过多种生化过程降解除草剂。除草剂的主要降解是通过磺酰脲桥的水解裂解和N（尿素桥）-C（嘧啶环）键的裂解而发生的。从农业土壤中分离出的黑曲霉菌株。