Isolation Of Phosphate-solubilizing Bacteria In Soybean Rhizosphere And The Analysis Of The Colonization For Bacteria

Lack of phosphorus in soil affected severely the growth of plants. It can reduce the phenomenon of phosphorus deficiency to some extent by adding the chemical phosphorus fertilizer artificially in the soil, but its effective utilization is less than25%. Therefore, this can result in waste of resource. In addition, the remnant chemical phosphorus fertilizer in the soil also can cause soil hardening, so it is easy to form a vicious circle. Currently, the research about biological phosphorus fertilizer attracted the attention of many scientists. On the basis of PVK plate screening combined with shake flask screening method, the study screened and identified the phosphate-solubilizing bacteria from the soybean’s rhizosphere of the northeastern China region, analyzed the phosphate-solubilizing bacteria’s application and its colonization in plant’s rhizosphere.1. The soil samples are selected from the soybean fields of Northeast region of China, the study used PVK plate screening method combined with NBRIP shake flask screening method to screen phosphate-solubilizing bacteria successfully. In addition, the study used molybdenum blues colorimetry to measure the ability of the bacteria’s phosphate solubilization.2. The study used CTAB method to extract bacterial DNA and made it as a template for PCR using bacterial universal primers, and the products of PCR were purified and sequenced. The results of sequencing showed that Zhaodong1strain, Acheng1strain and Hailun1strain had a higher sequence similarity with Bacillus megaterium; Beian4strain had a higher sequence similarity with Bacillus subtilis. In addition, the study identified the strains using optical microscope and scanning electron microscop.3. The study measured the change of soluble phosphorus which was applied the bacteria into the soil of soybean rhizosphere in pot experiment. The results showed that the one added bacteria increased the content of soluble phosphorus.4. Treating with the sand as a medium, we mixed a certain amount of Ca3(PO4)2and the culture, and inoculated the bacterias to that medium. The amount of soluble phosphorus was measured with direct extraction method and fast digestion method. The results showed that adding the phosphate-solubilizing bacteria can increase the content of soluble phosphorus in cultures.5. Soybean rhizosphere’s soil bacteria’s total DNA was extracted, and the DNA was amplified with "GC clip" primers. On the basis of the product of PCR purified, the degeneration gradient gel electrophoresis was performed to analyze the colonization of phosphate solubilizing bacteria in the soil. The results showed that two phosphate-solubilizing bacteria strains had an effective colonization in soybean rhizosphere’s soil.