Abstract:

Using calcium phosphate as insoluble phosphorus, high efficient phosphate solubilizing bacteria were isolated from rhizosphere soil of Pinus sylvestris var. mongolica. The halo ring method was used to isolate the phosphate-solubilizing bacteria, and the phosphorus-solubilizing efficiency was used to quantitatively screen the high efficiency strains. Physiological and biochemical test and 16S rRNA gene sequences analysis and phylogenic tree construction were employed to identify the genus of the phosphate-solubilizing bacteria. The effect of different carbon sources, nitrogen sources and C/N ratio on the phosphorus-solubilizing ability was studied by single factor method. The results showed that eleven strains of phosphate-solubilizing bacteria were isolated from the rhizosphere soil, strains A43 and A54 were quantitatively screened as the high efficiency strain. A43 and A54 were identified to be Pseudomonas koreensis. For strain A43, the phosphate-solubilizing ability was relatively good when the carbon source was glucose, nitrogen source was (NH₄)₂SO₄ and C/N was 20:1. For strain A54 the hosphate-solubilizing ability was relatively good when the carbon source was sucrose, nitrogen source was NaNO₃ and C/N was 20:1. The high efficiency phosphorus-solubilizing bacteria screened from the rhizosphere soil lay a good foundation for further preparation of growth-promoting microbial fertilizer of Pinus sylvestris var. mongolica.

Key words: Pinus sylvestris var. Mongolica, rhizosphere phosphorus-solubilizing bacteria, phosphorus-solubilizing ability, strain identification, microbial fertilizer