Abstract: The aim of this study was to isolate bacterial strains of azotobacter from the soil of Eucalyptus plantations with 10-year-old stands in Dongmen town, Fusui county, Chongzuo city, Guangxi Zhuang Autonomous Region, China, and to identify its genus by conventional methods, sequencing the Variable region(V1~V3) of gene of 16S rRNA and Biolog Automatic Microbial Identification System. The Variable region sequences of 16S rRNA gene was cloned by PCR method, KO108 is submitted to NCBI database with the accession number of KM460926.1,and the similarity values of 16S rRNA sequences between KO108 and Klebsiella oxytoca was above 99%. The similarity is greater than 0.5,which were 0.509 and 0.610 by using Biolog automatic microbial identification system respectively. The strain KO108 was indentified as Gram-negative acid-producing Klebsiella oxytoca belonging to the family of Enterbateriaceae genus Klebsiella. In addition, drug resistance of them was also detected by the disc agar diffusion test. The results showed that it was sensitive to nitrofurantoin, streptomycin, ceftriaxone, kanamycin, ofloxacin, doxycycline, ciprofloxacin, chloromycetin; and moderately sensitive to cotrimoxazole but resistant to polymyxin, penicillin G, tetracycline and erythromyc. The strain could be used as an object for genetic engineering, which laid the foundation for further study and transformation of nitrogen fixation microorganisms in forestry.

Key words: Klebsiella oxytoca, sensitive antimicrobials, molecular identification, Biolog system identi-fication