Isolation, identification and phosphate solubilization analysis of phosphate-solubilizing bacteria derived from banana rhizosphere soil

Abstract:

[Objective] In this study, ground phosphaterock was used as the undissolved phosphorus to select the high-efficient phosphate-solubilizing bacteria from the banana rhizosphere soil. [Methods] The methods of halo ring and Mo-Sb colorimetry were applied to isolate the phosphate-solubilizing bacteria. And a combination of morphologic alcharacteristics identification, physiological and biochemical test, 16S rRNA gene sequences analysis and phylogenic trees were employed to determine the genus of the phosphate-solubilizing bacteria. Various sources of carbon or nitrogen, the C/N value (40:1, 20:1, 8:1) and the pH value of culture medium which may affect the bacteria’s ability to dissolve the ground phosphate rock were studied with the single factor experimental method. [Results] Eight strains of phosphate-solubilizing bacteria (PSB) were isolated from the root soil, and three of them, B3-5-6, M-3-01, T1-4-01, were taken as representatives. The B3-5-6 was identified to be Bacillus aerophilus, M-3-01 Serratia nematodiphila and T1-4-01 Enterobacter asburiae. The phosphate-solubilizing ability of B3-5-6 and the pH of the culture medium was found to be linear negative correlated (|r|=0.949 66>0.735) and reached the extremely significant level. For strain B3-5-6, the phosphate-solubilizing ability was better when the carbon source was sucrose, nitrogen source was (NH4)2SO4 and C/N was 40:1. For strain T1-4-01, the phosphate-solubilizing ability was better when the carbon source was glucose, nitrogen source was (NH4)2SO4 and C/N was 20:1. For strain M-3-01, the phosphate-solubilizing ability was better when the carbon source was glucose, nitrogen source was (NH4)2SO4 and C/N was 20:1 for strain T1-4-01, the phosphate-solubilizing ability was better when the carbon source was lactose, nitrogen source was peptone and C/N was 20:1. The phosphate-solubilizing ability was raised 1.12 fold, 1.17 fold and 2.55 fold, respectively. [Conclusion] Various sources of carbon or nitrogen, and C/N could affect the phosphate-solubilizing ability of different strains. The phosphate-solubilizing ability of B3-5-6 and the pH of the culture medium was found to be linear negative correlated (|r|=0.949 66>0.735) and reached the extremely significant level. The phosphate-solubilizing mechanism of this strain needs to be furtherly investigated.

Key words:Rhizosphere soil, Phosphate-solubilizing bacteria, Phosphaterock, Identification, P-solubility