土霉素胁迫下反硝化聚磷菌的性能优化及菌剂制备

Performance optimization and agent preparation of a denitrifying phosphorus-accumulating strain under oxytetracycline stress

摘要:

背景 近年来，抗生素对自然水体的影响日益严重。由于抗生素具有杀菌性，会对活性污泥的沉降、絮凝性能以及微生物的群落结构产生影响，进而影响污染物的去除效果。目的 筛选1株同步去除氮磷的反硝化聚磷菌，探究其在土霉素胁迫下的生长情况并优化反应参数，制备微生物菌剂。方法 在土霉素胁迫条件下，从课题组长期培养驯化的反硝化聚磷系统中分离、筛选并纯化1株反硝化聚磷菌。运用16S rRNA基因序列及其生理生化特性的综合分析对菌株进行鉴定。同时，运用单因素与响应曲面法相结合研究了该菌的脱氮除磷能力，并采用发酵法制备微生物菌剂。结果 筛选出1株菌株P8，鉴定为成都肠杆菌(Enterobacter chengduensis)。对其脱氮除磷条件进行了优化，菌株P8在乙酸钠为碳源，浓度为3.32 g/L、pH 7.0、初始磷含量10 mg/L和30 ℃的条件下，对总磷和硝态氮的去除率可达69.6%和96.7%。菌剂载体选择麦麸混合玉米粉，质量比为8:2，菌剂在接种量为20 mL时效果最好。结论 筛选出1株能同步去除氮磷的菌株E. chengduensis P8，在土霉素胁迫下生长良好，为土霉素污染环境的微生物修复提供了种质资源和科学依据。

Abstract:

Background In recent years, the pollution of antibiotics in natural water bodies has been aggravating. Because antibiotics can kill bacteria, they change the sedimentation and flocculating properties of sludge and affect the types of microorganisms living in the water, making it harder to remove pollutants.Objective Screening of a strain of denitrifying phosphorus-polymerizing bacteria for simultaneous removal of nitrogen and phosphorus, investigation of its growth under oxytetracycline stress and optimization of reaction parameters for the preparation of microbial agents.Methods In this study, we picked out, tested, and purified a strain P8 under oxytetracycline stress from a denitrifying and phosphorus- accumulating system which had been acclimated for a long time. Based on the 16S rRNA gene sequence and physicochemical properties identify this strain. Single factor tests and response surface methodology were employed to optimize the denitrifying and phosphorus-removing conditions of this strain and preparation of microbial agents by fermentation method.Results The results showed that this strain was identified Enterobacter chengduensis. And it could grow normally under oxytetracycline stress. The strain was able to remove 69.6% of total phosphorus and 96.7% of nitrate nitrogen under the conditions of 3.32 g/L sodium acetate as the carbon source, pH 7.0, an initial phosphorus level of 10 mg/L, and 30 ℃. The microbial agent carrier was composed of wheat bran and corn flour in an 8:2 mass ratio, with optimal efficacy observed at an inoculation volume of 20 mL.Conclusion We screened out a strain E. chengduensis P8 that can simultaneously remove nitrogen and phosphorus and good growth under oxytetracycline stress. This work provides new resources and scientific support for using microorganisms to remedy the environments polluted by oxytetracycline.