| Phosphate solubilizing microorganisms play an important role in the transformation of phosphorus in the soil,which can make the insoluble phosphorus that can not be absorbed by the plant to transform into available phosphorus.In the present study,3 high efficient phosphate solubilizing strains were isolated from the Maize rhizosphere soil in the long-term location experiment field of Jilin Agricultural University and were identified.In addition,the conditions,abilities and characteristics of phosphate-solubilizing of the 3 strains were systemically investigated,the ability to produce IAA and siderophore was determined and the effects of phosphate solubilizing bacteria on Maize growth were investigated.This will provide high quality strains for the development of high efficient phosphate solubilizing bacteria fertilizer,increase phosphorus utilization,reduce the application amount of chemical phosphorus fertilizer,and then reduce the agricultural non-point source pollution caused by the application of phosphate fertilizer.The results are as follows:1.By means of phosphorus solubilizing rescreening,2 high efficient phosphate solubilizing strains were obtained and named XS2,XF1.According to the results of physiological and biochemical characteristics and 16 SrDNA sequence analysis,the stains XS2 and XF1 belong to the genus Bacillus.2.The best phosphate-solubilizing conditions of the 2 strains were investigated.Using L25(53)orthogonal test,the culture conditions were optimized from the aspects of carbon source,nitrogen source and pH value.The results showed that the best phosphate-solubilizing conditions of the strains XS2 and XF1 were glucose as carbon source,ammonium sulfate as the nitrogen source and pH 5.The strains have a good phosphate dissolving effect in the temperature range of 25?~45?,and the maximum amount of soluble phosphorus appears at a temperature of 35?.By means of dynamic analysis of phosphorus solubilizing,the phosphate solubilizing strains showed different phosphate solubilizing ability for different insoluble phosphorus.The phosphate solubilizing ability of the strain XS2 for different insoluble phosphorus was as follow: Ca3(PO4)2 > phosphate rock powder > AlPO4 > FePO4,and that of the strain XF1 was as follow: Ca3(PO4)2> AlPO4>phosphate rock powder >FePO4.The results of dynamic analysis of phosphorus solubilizing showed that before 3 days,and the amount of dissolved phosphorus increased.There was a significant negative correlation between the amount of the strain XS2 and XF1 and pH of fermentation broth,the correlation coefficients were-0.876 and-0.83(p<0.01).Different calcium phosphate concentration affected phosphate solubilizing ability of the strains.When the concentration of calcium phosphate was 5 g·L-1,thephosphate solubilizing capacity was the highest.3.The phosphate solubilizing bacteria secreted organic acid in the process of dissolving insoluble phosphorus,the types and contents of organic acids was different,and the organic acids produced under different nitrogen and carbon sources were also different.Oxalic acid,malic acid,acetic acid,citric acid,lactic acid,succinic acid and several unknown acids were detected by HPLC.4.The disease resistance and growth promoting ability of the phosphate solubilizing strains were investigated.The results showed that the strains XS2,XF1 can produce siderophore,the ability of the strains XS2 and XF1 to produce IAA was stronger,and the strains XS2,XF1 had different inhibitory effects on Alternaria solani,ginseng root rot pathogen,Fusarium solani,Rhizoctonia solani,Fusarium graminearum.5.The phosphorus accumulating capacity of the strains XS2 and XF1 was investigated.The phosphorus accumulating ability of the trains XS2 and XF1 was identified by the PAM medium culture and dyeing microscopic examination of metachromatic granules.The maximum phosphorus removal rate measured by liquid cultivation were 44.45% and 19.27%. |
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