紫外诱变选育高原环境絮凝菌及其絮凝条件优化

为获得耐低温且絮凝优异的絮凝菌，对一株分离得到的絮凝菌进行紫外诱变和5℃低温胁迫培养，并对诱变优势菌进行应用条件优化.结果表明:①原始菌为蜡状芽孢杆菌（Bacillus cereus）.②紫外诱变和低温胁迫培养得到的目标诱变菌FB-5对生活污水絮凝率达75.35%，具有良好的遗传稳定性.③单因素试验确定最佳絮凝条件，即絮凝菌投加量为0.90 mL/（50 mL）、pH为7.4、助凝剂加量为1.0 mL/（50 mL）、处理时间为15 min；筛选出影响诱变菌絮凝能力最显著的3个因素为絮凝菌投加量、pH和助凝剂加量；通过Box-Behnken响应面试验得到最佳净化的应用条件，即絮凝菌投加量为0.90 mL/（50 mL）、pH为7.38、助凝剂加量为1.04 mL/（50 mL）.④验证试验确定絮凝率达97.01%，BOD₅、COD_Cr、浊度和色度去除率均达到97%以上，出水水质满足GB 18918—2002《城镇污水处理厂污染物排放标准》一级A标准.研究显示，紫外诱变联合低温胁迫技术以及单因素与响应面结合优化絮凝条件可以大幅度提高原始菌株的絮凝能力，低温诱变菌FM-5能使高寒地区城市生活污水中悬浮固体大幅降低，同时去除水体中多种污染物. 

Mutation Breeding of Flocculating Microorganism in Plateau Area by Ultraviolet and Its Application by Optimization

In order to obtain a flocculating microorganism with low-temperature resistance and excellent flocculation, UV mutagenesis and cultivation under low temperature (5℃) stress were used for flocculating microorganism separation. The results showed that:(1) The original flocculating strain was preliminarily identified as Bacillus cereus; (2) The screening gave the targeted mutant FM-5 with 75.35% flocculating rate with genetic stability; (3) Optimum flocculating conditions were determined as optimum dosage 0.90 mL/(50 mL), pH 7.4, coagulant aids 1.0 mL/(50 mL), and processing time 15 mins via univariate experiments (UE); the Box-Behnken response surface method (RSM) was used to acquire the optimum combination of application conditions:dosage 0.90 mL/(50 mL), pH 7.38, coagulant aids 1.04 mL/(50 mL); (4) Verification tests verified that the flocculating rate reached 97.01%, and BOD₅, COD_Cr, turbidity and chroma removal rates reached more than 97%, and the effluent quality met the GB 18918-2002 1 A standard of the Urban Sewage Treatment Plant Pollutant Discharge Standard. In conclusion, the flocculating ability of the original strains could be greatly improved via UV mutagenesis, cultivation under low temperature and a combination of UE and RSM, hence FM-5 could reduce more suspended solids in municipal sewage and achieve removal of various pollutants simultaneously in a plateau area.