一株具有荧蒽降解能力的产吲哚乙酸菌的筛选鉴定及其特性

从植物根际土壤中筛选出能分泌吲哚乙酸(3-indole acetic acid,IAA),并对荧蒽具有一定降解效果的菌株ZZ21.30℃、180 r/min摇床培养24 h,能产生39.81 mg/L IAA,静息细胞对50 mg/L荧蒽转化7 d后,降解率达25.61%.此外,该菌还耐盐碱,能解磷,在pH为10、含盐度为7%的LB培养基上能够生长,30℃培养72h对磷酸三钙液体培养基的溶磷量达120.86 mg/L.经形态学观察、部分生理生化特征测定以及16S rDNA的保守序列鉴定,初步确定该菌株为耐盐节杆菌(Arthrobacter pascens).为促进菌株生长,提高菌株IAA产量,设定了基于培养时间、初始pH、通气量、温度、不同碳源和氮源的单因素菌株发酵条件优化实验,结果表明,促进菌株生长和提高IAA分泌的最佳培养条件并不完全一致,综合考量得到最佳发酵培养条件是初始pH为6,装液量为45 mL/150 mL,28℃摇床培养15 h,最佳碳、氮源分别是甘露醇和酵母粉.在最佳单因素优化条件下菌株产IAA能力最强可达92.31 mg/L.

Isolation and characterization and fluoranthene degrading of an IAA secreting bacterial strain

An indole-3-acetic (IAA)-producing strain ZZ21 was isolated from the rhizosphere, which could degrade fluoranthene. After 24h' shaking (30℃, 180 r/min), the strain could produce 39.81 mg/L IAA, and when the strain was grown in the 50 mg/L fluoranthene for 7days, the degradation rate was 25.61%. Besides, the strain could grow in LB medium under the pH of 10 and the salinity of 7%. When the ZZ21 was inoculated into PKO liquid culture, the release of maximal available soluble phosphorus reached to 120.86 mg/L after 72 h incubation at 30℃. This strain was identified as Arthrobacter pascens by its morphology,physiological and biochemical characteristics and 16S rRNA sequence.In order to promote the ZZ21 growth and improve the IAA production, a fermentative optimization experiment with single factor test was designed, based on incubation time, initial pH, ventilatory capacity, temperature and different carbon source as well as nitrogen source. Results showed that the best culture condition for both ZZ21 growth and IAA production are not the same. Overall, the optimal conditions were initial pH of 6, liquid volume of 45 mL/150 mL, temperature of 28℃, and shaking time of 15h, besides, the best carbon and nitrogen sources were mannitol and yeast, respectively. And the IAA production of ZZ21 could reach a highest level of 92.31 mg/L.