MCPA-Na除草剂降解菌的分离及发酵条件优化

Isolation of MCPA-Na Degrading Bacteria and Optimization of Fermentation Conditions

从长期受MCPA-Na污染的土壤中经过富集培养分离纯化得到4株MCPA-Na降解菌株KE-01 (KY274847)、KE-02 (KY274848)、KE-03 (KY303833)、KE-04 (KY274849),并利用紫外分光光度法对其进行降解性能测定。经生理生化实验和16S rDNA序列分析鉴定4株菌株均属芽孢杆菌属(Bacillus sp.),KE-01与Bacillus oceanis ediminis gene相似度达到100%,KE-02与Bacillus pumLius strain 3-2相似度达到100%,KE-03与Bacillus toyonensis strain J1相似度达到100%,KE-04与Bacillus pumilus strain BS25相似度达到100%。通过对4株菌株进行的降解特性研究表明:菌株KE-04降解效果最佳,通过对菌株KE-04进行响应面法进行优化,在以5.0%蔗糖为碳源,2.0%的酵母浸粉为氮源,NaCl浓度0.41%,pH为7.8的培养基中培养时降解效果最佳,可达到69.56%。

The four degrading bacteria strain KE-01(KY274847), KE-02(KY274848), KE-03(KY303833) and KE-04 (KY274849), were isolated and purified form the field soil which have been applied with herbicide MCPA-Na for many years by enrichment culture. Based on the 16S rDNA identification, these 4 bacteria had been identified as Bacillus sp., the similarity between the KE-01 sequence and Bacillus oceanis edimins gene sequence reached 100%, and the sequence similarity of KE-02 and Bacillus pumLius strain 3-2 reached 100%, the similarity between the KE-03 sequence and Bacillus toyonensis strain J1 sequence reached 100%, the similarity sequence between KE-04 and Bacillus pumilus strain BS25 sequence reached 100%. By degrading characteristic analysis, KE-04 is the most efficacious in 4 bacteria. The experiment showed that the optimum growth conditions of strain KE-04 was sucrose 5.0%, yeast extract powder 2.0%, NaCl 0.41%, pH 7.8, and the concentration of MCPA-Na is 0.1% after single factor processing and response surface methodology. The degradation rate reached 69.56% after 48 h culturing under these conditions.