Screening and characteristics of phosphate-solubilizing bacteria in rhizosphere of 7 grasses on eastern Qilian Mountains

Phosphate dissolving bacteria had been isolated from rhizosphere of 7 kinds of grasses based on PKO and Mehknha culture media. The results showed that there were different colony characteristics in growth rate, color, shape, edge integrity, as well as the surface condition of the ridge in different bacteria strains. The number of inorganic phosphate solubilizing strains from rhizosphere of Achnatherum inebrians showed that soil adhering to roots＞rhizoplan or surface of roots＞histoplan or interior of roots, strains from others grasses were rhizoplan or surface of roots＞soil adhering to roots＞histoplan or interior of roots distribution trend. In the first 10 days, most of the dissolved inorganic phosphorus strain’s D/d stabilized, but most of the dissolved organic phosphorus strain stabilized in the first 14 d. Phosphorus solubilizing capability of the strains were determined by the molybdenum blue spectrophotometry, the results indicated that there were lager differences in 109 phosphatedissolving microorganisms capability, phosphate concentration was between 0.47～582.46 μg·mL-1, of which strain PCRP5 had the highest phosphate solubilization capacity. For the 143 strains organic phosphate dissolving bacteria, the ability to dissolve organic phosphorus was large (concentration was 0.07～14.76 μg·mL-1), the highest P concentrations was strains MCMRS4. There were no obvious relationship between the organic phosphorus strains solubilization capacity and pH (P＞0.05), however pH of PKO showed significant negative relationship with the organic phosphorus strains P concentration (P＜0.01).