一株高效阿特拉津降解菌株的筛选及其降解能力和机理

Screening and identification of an atrazine-degrading strain and its degradation capacity and mechanism on atrazine

在江苏省某玉米农田土壤中筛选出以阿特拉津(ATZ)为唯一碳源和氮源的菌株D2,经16S rDNA基因序列分析,将其鉴定为土壤芽孢杆菌(Solibacillus),菌株D2的生长曲线符合SGompertz模型和Slogistic模型.不同ATZ初始浓度、pH和培养温度条件下对ATZ的降解实验表明,菌株D2对ATZ具有极高的耐受性(>200 mg·L^(−1)),在温度为20—30℃、pH值为5—9的条件下降解率均能达100%,可将100 mg·L^(−1)的ATZ在18 h内完全去除,ATZ去除量与D2菌株的数量呈显著的负相关(r=−0.983,P<0.01).对ATZ的降解中间产物测定表明,菌株D2可通过脱氯羟基化、加氢脱烷基化、甲基化、脱烷基化和水解等过程将阿特拉津转化为羟基阿特拉津(HA)、阿特拉通(atraton)、脱乙基阿特拉津(DEA)、西玛津(DMA)、羟基西玛津(HDMA)和脱乙基脱异丙基阿特拉津(DACT).因此,D2是一株高效降解菌株,环境适应能力高于大部分已报道菌株,能够广泛应用于ATZ污染废水和污染土壤修复等领域.

Strain D2,using atrazine(ATZ)as the only carbon source and nitrogen source,was isolated from a maize field in Jiangsu Province.It was preliminarily identified as Solibacillus by 16S rDNA gene sequence analysis,and its growth curve both fit SGompertz model and Slogistic model.Experiments demonstrated that under different initial ATZ concentration,pH and temperature,strain D2 could tolerate high concentration of ATZ(>200 mg·L^(−1)),wider pH and temperature,compared with reported strains.Strain D2 degraded ATZ from 100 mg·L^(−1)to 0 mg·L^(−1)within 18 h at 20—30℃,pH 5—9,and there was a significant negative correlation between the amount of ATZ removal and the population of D2 strain(r=−0.983,P<0.01).Analysis of the degradation intermediates of ATZ revealed that strain D2 transformed atrazine into hydroxy atrazine(HA),atraton,simazine(DMA),deethyl atrazine(DEA),hydroxy simazine(HDMA)and desethyldesisopropyl atrazine(DACT)through dechlorination hydroxylation,hydrodealkylation,methylation,dealkylation and hydrolysis.Therefore,strain D2 is a strong degrading strain with better environmental adaptability than most reported strains,and could be used widely in the remediation of ATZ wastewater and contaminated soil.