桑树根际固氮细菌的分离鉴定及固氮酶活力测定

Isolation,Identification and Nitrogenase Activities of Mulberry Rhizosphere Azotobacter

利用固氮细菌可降低桑园化肥使用量和提高桑叶产量与品质。采用选择性培养基,从桑树根际分离获得24个具有固氮能力的细菌分离株,以rep-PCR基因指纹分析聚类为18个聚类群。经固氮酶活性测定,PA19、PA2和PK1菌株具有较强的固氮酶活性。利用菌落形态特征观察及16S rDNA碱基序列测定和同源性分析,对3株细菌进行鉴定的结果是:PA19菌株为中慢生根瘤菌属(Mesorhizobium sp.),PA2菌株为假单胞菌属(Pseudomonas sp.),PK1菌株为土壤杆菌属(Agrobacterium sp.)。

Twenty-four bacterial isolates that had nitrogenase activities were obtained from mulberry rhizosphere by the plate cultivation method with selective media, and were divided into 18 clusters by means of the Repetitive-element PCR （rep-PCR） fingerprints cluster analysis. The nitrogenase activities of these isolates were determined. The results showed that PA19, PA2 and PK1 strains had high nitrogenase activities. By means of phenotypic characteristics and phylogenetic analysis of 16S rDNA sequences of 3 strains, we found that PA19 belonged to Mesorhizobium sp., PA2 belonged to Pseudomonas sp., and PK1 belonged to Agrobacterium sp.