Growth Conditions and Growth-promoting Characteristics of an Endophytic Bacterium from Toxicodendron succedaneum

PurposeAn endophytic bacterium named BSH-1 was isolated and selected from the sterile seedlings of Toxicodendron succedaneum, which could produce indole-3-acetic acid (IAA), to identify it and to analyse its growth-promoting characteristics, providing theoretical basis for the development of microbial fertilizer.

MethodsThe morphology of strain BSH-1 was observed by Gram staining and identified by 16S rRNA gene sequence analysis. The optimum growth temperature, pH and NaCl mass concentration were tested by growth curve. The ability of IAA production was determined by Salkowski chromogenic assay. Seeds of rice, Pinus yunnanensis and P. kesiya var. langbianensis were soaked in different densities of fermentation broth, and the growth-promoting characteristics were analysed by the germination rate of seeds and the effects of suspension on rice seedling height, stem diameter, root number, and root length.

ResultsStrain BSH-1 was identified as Bacillus subtilis, and its growth was the largest at 35 ℃, pH 7 and 10 g/L NaCl, and the IAA production capacity reached 17.27 mg/L. It could promote plant growth by promoting plant height, stem diameter, and root number of rice seedlings. The plant height and root number of rice seedlings were 9.0% and 20.8% higher than those of the control, respectively.

ConclusionB. subtilis BSH-1 can produce IAA and promote the growth of rice seedlings. It has potential application value in promoting plant growth and development.