[Growth and degradation characteristics of an efficient and broad-spectrum atrazine-degrading strain SB5].

In this study, triazine-degrading strain SB5 was isolated and screened from the activated sludge contaminated with atrazine by enrichment culture technology. Based on its morphology and 16S rRNA gene analysis, strain SB5 was initially identified as Paenarthrobacter sp. It contained the atrazine-degrading genes trzN, atzB, and atzC. The addition of glucose, sucrose, sodium citrate, yeast extract and peptone to the culture medium significantly increased the biomass and atrazine degradation efficiency of strain SB5. The addition of (NH4)2SO4 and NH4Cl inhibited the biomass of strain SB5, but did not affect its degradation efficiency for atrazine. The addition of starch did not affect the biomass of strain SB5, but significantly inhibited its degradation for atrazine. Strain SB5 showed good atrazine tolerance and atrazine degradation ability in the temperature range of 4-42 ℃, initial pH of 4-10 and initial concentration of 50-1000 mg·L-1. Using 100 mg·L-1 atrazine as the sole carbon source, the strain SB5 degraded 100% of atrazine within 36 h under the optimal conditions of 37 ℃ and initial pH 8.0. The results of degradation spectrum analysis showed that strain SB5 had a good degradation effect on the six triazine herbicides (simazine, terbuthylazine, propazine, cyanazine, ametryn and prometryn) at an initial concentration of 100 mg·L-1, and the degradation rates were 86.4%, 92%, 98.6%, 95.6%, 100% and 99.2% after 48 h of incubation, respectively. The results demonstrated that SB5 was an efficient and broad-spectrum degradation strain. The strain SB5 further enriched the strain resources for atrazine biodegradation, and its high-efficient and broad-spectrum degradation characteristics for triazine herbicides showed a potential application value in the development of bioremediation technology for the pollution of triazine herbicides.本研究采用富集培养技术自莠去津污染的活性污泥中分离筛选到一株具有降解三嗪类除草剂功能的菌株SB5,经形态学和16S rRNA基因分析将其初步鉴定为类节杆菌属细菌。其具有已知莠去津降解相关基因trzN、atzB及atzC。在培养基中添加葡萄糖、蔗糖、柠檬酸钠、酵母浸粉和蛋白胨可显著提高菌株SB5的生物量和对莠去津的降解效率;外加(NH4)2SO4和NH4Cl对该菌生物量起到抑制作用,但不影响其对莠去津的降解效率;外加淀粉对菌株的生物量影响不显著,但会影响其对莠去津的降解。菌株SB5在4～42 ℃、4～10初始pH及50～1000 mg·L-1莠去津初始浓度范围内均具有较好的莠去津耐受性和莠去津降解能力。以100 mg·L-1莠去津为唯一碳源,在37 ℃、初始pH 8.0的最佳条件下,菌株SB5在36 h内对其降解率可达到100%。降解谱分析结果表明,菌株SB5对100 mg·L-1初始浓度的西玛津、特丁津、扑灭津、氰草津、莠灭净和扑草净6种三嗪类除草剂同样具有较好的降解效果,培养48 h后的降解率分别为86.4%、92%、98.6%、95.6%、100%和99.2%,是一株高效广谱的降解菌。菌株SB5进一步丰富了莠去津生物降解的菌种资源,其对三嗪类除草剂的高效和广谱降解功能赋予其在三嗪类除草剂复合污染的生物修复和治理技术研发方面的潜在应用价值。.