Phosphate-solubilizing Characteristics and Growth-promoting Effect of Sinorhizobium meliloti CHW10B on Taxus chinensis var. mairei

Objective  A phosphate-solubilizing bacterium, Sinorhizobium meliloti CHW10B, was selected from Taxus chinensis var. mairei. Its phosphate-solubilizing characteristics and growth-promoting effect on T. chinensis var. mairei were studied.

Method  The effects of culture time, Ca₃(PO₄)₂ concentration, carbon sources, nitrogen sources, initial pH, liquid filling volume, salt ions and other environment factors on phosphate solubilizing ability of strain CHW10B were studied by liquid fermentation experiment. Pot experiment was conducted to evaluate the role of strain CHW10B in promoting the growth of T. chinensis var. mairei. Some growth-promoting mechanism such as producing ACC deaminase, siderophore, indoleacetic acid, arginine decarboxylase and organic acid were determined.

Result  The results showed that CHW10B strain displayed the highest phosphate-dissolving capacity when the cultivation period was 4 days, the amount of calcium phosphate was 5.00 g·L^-1, the initial pH reached 7.0, the volume of liquid was 1/2, the NaCl concentration was 0.0 g·L^-1 and the temperature was 30℃. The phosphate solubilizing capacity of the strain got the highest when using glucose as carbon source and ammonium sulfate as nitrogen source. Moreover, the ratio of carbon to nitrogen (100:1) is optimum for strain CHW10B. After being inoculated with strain CHW10B, the ground diameter, seedling height and biomass of 1-year-old T. chinensis var. mairei seedlings increased by 19.53%, 20.14% and 25.39% in 360 days' post-inoculation, respectively. The strain could produce siderophore, arginine decarboxylase, ACC deaminase (0.922 U·mg^-1) and IAA (8.908 mg·mL^-1), and secrete a large amount of gluconic acid (5 704.92 μg·L^-1).

Conclusion  S. meliloti CHW10B has strong phosphorus-solubilizing capability, and plays a significant promoting role in the growth of T. chinensis var. mairei. The strain can be applied to a variety of soils of different acidity-alkalinity. The result would be an important reference for further exploring of the CHW10B strain in production of bio-fertilizer and high efficient cultivation on T. chinensis var. mairei, etc.