Abstract:

Phosphate-solubilizing bacteria (PSB) plays an important role in improving soil fertility and soil health by converting insoluble P forms to soluble forms accessible by plants, and it is necessary to know phosphate solubilization mechanism in order to apply. This study assessed the phosphate solubilizing ability of a high efficiency PSB strain, PSB28, and investigated the mechanism of phosphate solubilization by comparing growth conditions inoculated in medium Ca3(PO4)2 as the sole phosphorus source with K2HPO4 as the sole phosphorus source. The results showed that in the medium with Ca3(PO4)2, logarithmic phase was longer, but the maximum concentration of biomass was larger. pH showed decreasing gradually, which was higher than that of K2HPO4 as the sole phosphorus source. HPLC results showed both the sorts and the quantity of organic acids in Ca3(PO4)2 medium were complicated than that of K2HPO4 medium. The activity of acid phosphatase was a little higher. All the results suggested that organic acids excretion by PSB28 might be the main reason and acid phosphatase had an indirect effect on P solubilization.