[Screening and identification of indoleacetic acid producing endophytic bacterium in Panax ginseng]

Endophytic bacteria which was producing indoleacetic acid was screened from Panax ginseng by using the Salkowski method. The active strain was also tested for its ability of nitrogen fixation by using the Ashby agar plates, the PKV plates and quantitative analysis of Mo-Sb-Ascrobiology acid colorimetry was used to measure its ability of phosphate solubilization, for its ability of potassium solubilization the silicate medium and flame spectrophotometry was used, for its ability of producing siderophores the method detecting CAS was used, for its ability of producing ACC deaminase the Alpha ketone butyric acid method was applied. And the effect on promoting growth of seed by active strain was tested. The results showed that the indoleacetic acid producing strain of JJ5-2 was obtained from 118 endophytes, which the content of indoleacetic acid was 10.2 mg x L(-1). The JJ5-2 strain also had characteristics of phosphate and potassium solubilization, nitrogen fixation, producing siderophores traits, and the promoting germination of ginseng seeds. The JJ5-2 strain was identified as Bacillus thuringiensis by analyzing morphology, physiological and biochemical properties and 16S rRNA gene sequences.