【摘要】 从城市污水处理厂活性污泥中分离得到一株能以磺胺二甲基嘧啶（SM2）为唯一碳源的菌株,经生理生化鉴定和16S rRNA基因序列同源性分析,将此菌鉴定为蜡样芽孢杆菌（Bacillus cereus）,命名为J2.不同条件下的降解特性研究结果表明,J2菌株具有极高的SM2耐受性(100 mg·L^-1)、较广的温度（20～30℃）和pH（6～8）适用范围;在温度30℃、pH=8.0、初始OD₆₀₀=0.1、SM2起始浓度为50 mg·L^-1的条件下,J2菌株在36 h内对SM2的降解率可达100%,降解效率远超目前已报道的其他SM2降解菌株,展现出了良好的应用潜力.J2菌株降解SM2过程中产生了5种主要中间代谢产物,分析推断其降解SM2的途径分为两条:①磺胺二甲基嘧啶分子首先在酶促反应作用下脱除SO₂,生成嘧啶环和苯胺环自由基,这两种自由基再经过环间耦合生成N-（4,6-二甲基嘧啶-2基）-1,4-二苯胺,该分子中的C—N键在活性氧物种的作用下断开生成苯胺和2-氨基-4,6-二甲基嘧啶;②在漆酶的作用下N⁴键断裂,产生N-（3,5-二甲基嘧啶）-苯磺酰胺,之后N-（3,5-二甲基嘧啶）-苯磺酰胺的N—S键断裂,进一步形成2-氨基-4,6-二甲基嘧啶和苯亚砜.更多还原

【Abstract】 In the present study, a bacterial strain isolated from the activated sludge of an urban wastewater treatment plant was employed to degrade sulfamethazine. According to the phenotype, physiological, biochemical analyses and 16 S rRNA sequence analysis, the strain was preliminary identified as Bacillus cereus and designated as J2. J2 has high SM2 tolerance(100 mg·L^-1), the broad temperature（20～30 ℃） and pH（6～8） adaptability. Results show that 50 mg·L^-1 SM2 was completely degraded in 36 h at 30 ℃, pH 7.0 with OD₆₀₀ at 0.1. J2 also exhibits higher tolerance and degradation efficiency than other SM2-degrading strains. Five intermediates were identified by LC-MS/MS analysis, two probable degradation pathways of SM2 by J2 was tentatively proposed: ①SO₂ was firstly removed from the SM2 molecules under the action of enzymatic reaction to generate pyrimidine and aniline radicals and then N-（4,6-dimethylpyrimidine-2）-1,4-diphenylamine was generated through ring coupling reaction between the two radicals, and the C—N bond subsequently broke off to the form phenylamine and 2-amino-4,6-dimethylpyrimidine by the attack of reactive oxygen species. ②The N⁴ bond was broken through the action of laccase, producing N-（4-hydrosulfonylphenyl）-3,5-dimethylaniline, and then the N—S bond was broken to form 2-amino-4,6-dimethylpyrimidine and hydrosulfonylbenzene.更多还原