[Screening and identification of an endophytic bacterium with 1-aminocyclopropane-1-carboxylate deaminase activity from Panax ginseng and its effect on host growth].

OBJECTIVE

This study aimed to screen endophytic bacteria with 1-aminocyclopropane-1-carboxylate deaminase activity from Panax ginseng and test the capability of growth promotion to its host.

METHODS

In total 120 endophytic bacterial strains isolated from Panax ginseng were screened for 1-aminocyclopropane-1-carboxylate deaminase activity using the qualitative and quantitative methods. The obtained strain was also tested for its ability of nitrogen fixation using the Ashby agar plates and the gene of nifH, for its ability of phosphate solubilization using the Pikovaskaia's plates and quantitative analysis of Mo-Sb-Ascrobiology acid colorimetry, for its ability of producing siderophores using the method of Chrome azurol S detecting, and its effect on promoting growth of Panax ginseng by laboratory and field experiments. The bacterial strain with ACC deaminase was identified based on morphology, physiological and biochemical traits, and 16S rRNA sequence analysis.

RESULTS

The bacterial stain JJ8-3 with the ability of producing ACC deaminase activity was obtained through screening, which its ACC deaminase activity was alpha-ketobutyric acid 6.7 micromol/(mg x h). Strain JJ8-3 had other traits of phosphate solubilizing, nitrogen fixation, producing siderophores, and the ability of promoting growth of Panax ginseng. Strain JJ8-3 was identified as Pseudomonas fluorescens.

CONCLUSIONS

Strain JJ8-3 of endophytic bacterium with ACC deaminase activity from Panax ginseng was obtained and would lay the foundation for its further study and application on plant growth promotion.