Isolation And Identification Of Saline Tolerance Phosphate-Solubilizing Bacteria And Their Effects On Growth Of Glycyrrhiza Uralensis Fisch Under Saline Stress

Phosphorus (P), one of the major plant growth-limiting nutrients, is mostly insoluble in soils and therefore unavailable to plants. The saline-alkali soil is characterized with high salt, low nutrition and strong sorption and buffer capacity which lead to low phosphorus availability. Phosphate solubilizing bateria (PSB) could solubilize insoluble P and supply P to the plants sustainably in the soils. The PSB is widely present in soil and might play a fundamental role in this process. In this paper, the salt-affected soils of beach from Tianjin China were sampled to screen the saline-alkali tolerance phosphate-solubilizing bacteria (SA-T-PSB) using inorganic phosphorous medium, and the plant growth promotion of the stains on Glycyrrhiza uralensis Fisch is studied, too.The results were described as follows.Four salt-tolerance PSBs which have plant growth promotion ability were isolated from the soil samples. On basis of 16S rRNA gene sequencing and the phenotypic characterization, these four isolates, B1114, B1213, B1303 and J101 were identified as Enterobacter ludwigii (JX215328), Pantoea ananatis (JX215331), Pseudomonas psychrotolerans (JX215329) and Gluconobacter frateurii (JX215320), respectively.Organic acid types of the isolates were determined by high performance liquid chromatography (HPLC), and the results showed that all 4 isolates mainly secreted gluconic acid. We also studied the effect of carbon and nitrogen source on the P-solubilizing ability of strain J101, which J101 utilizing the glucose as single carbon source was much higher than using other carbon source in soluble P content of culture, while there was no significant difference on the P solubilization activity when in various nitrogen source.P-solubilizing activity (PSA) of the selected PSBs were carried out under saline stress. No significant differences were recorded in solubilization at 0～1.5% NaCl for all isolated strains. The growth and phosphate solubilizing amount of strains B1114, B1213, B1303 had no significant change among pH 5-9, and strains J101 had max phosphate solubilizing amount with pH 7.5.The pot experiment indicated that the strains B1303 and J101 could increase the avaible P and change the microbial community structures. A significant increase in parameters growth of Glycyrrhiza uralensis Fisch was recorded for PSB inoculation treatment compared with control. The P levels in both shoot and root were also improved by inoculation with PSBs, with 62%-78% in P level. By HPLC analysis, the PSB inoculation treatment showed increase in total glycyrrhizic acid and flavonoids contents in the roots.In conclusion, the selected phosphate solubilizing bacteria B1303 and J101 could perform the phosphate solubilizing activity and supple aviable P for plant under saline stree in saline-alkali soils...