Phosphate Solubilizing Characteristics Of Two Strains Of Phosphate Solubilizing Actinomycetes And Preliminary Study On Their Resistance To Disease And Promoting Growth

In order to fully and efficiently mobilize the resource of soil phosphorus,reduce the amount of phosphate fertilizer,and lighten the problem of agricultural pollution caused by excessive use of phosphate fertilizer.In this experiment,the maize rhizosphere soil was used as the material to screen the actinomycetes,which had the ability to Dissolve Phosphorus by NBRIP identification medium,and to carry out physiological,biochemical and molecular identification of Actinomycetes with strong phosphate solubilizing ability.The content of soluble phosphorus in the fermentation broth was determined by the Mo-Sb colorimetry.The phosphate solubilization conditions were optimized from the different medium,carbon source,nitrogen source,initial pH and phosphorus sources.The effects of different concentrations of EDTA on the phosphorus solubilization of phosphate solubilizing Actinomycetes were analyzed under the optimum conditions.HPLC method was used for the determination of organic matter in the fermentation liquid.The mechanism of phosphate solubilizing by phosphor actinomycetes was preliminarily analyzed.The plate confrontation method was used to identify the culture medium,and the disease resistance and life promoting ability of the strain were investigated.The results of the study are as follows:1.Seven phosphate solubilizing actinomycetes were obtained in the experiment.Among them,the amount of phosphate solubilizing SY7 and SX3 exceeded 200mg/L.2.The strain SY7 and SX3 were identified by the culture characteristics,physiological and biochemical characteristics and the determination of 16S rDNA sequence.The strain SY7 and SX3 belonged to the genus small monospora.In taxonomic status,the strain SY7 was closely related to the small monospora black monospora?Micromonospora nigra?.In taxonomic status,the strain SX3 and crimson red were small.Micromonospora purpurea is closely related.3.Different medium,carbon source,nitrogen source,initial pH and phosphorus source were used to optimize the optimum conditions for phosphorus dissolution of SY7 and SX3 of actinomycetes.The results showed that the maximum dissolving amount of SY7 to calcium phosphate was 387.87mg/L under the condition of glucose as carbon source,ammonium sulfate as nitrogen source and initial pH8;with sucrose as carbon source and KNO₃ as a nitrogen source.Under the initial pH7 condition,the dissolution rate of strain SX3 to calcium phosphate is the highest,reaching306.18mg/L.4.Different concentrations of EDTA affect phosphate solubilizing ability of phosphate solubilizing bacteria,showing low concentration and high concentration inhibition.Under the optimal solution of strain SY7,the content of soluble phosphorus in the fermentation broth was the highest and reached 575.3mg/L.When the concentration of the fermentation liquid was 4.0mg/mL,the content of soluble phosphorus in the fermentation liquid decreased,and the soluble phosphorus content in the fermentation liquid was lower than the control level when the concentration of EDTA was 8mg/mL.Under the optimal solution of strain SX3,the content of soluble phosphorus in the fermentation broth was the highest and reached 493.75mg/L.When the concentration of 1.0mg/mL was EDTA,the soluble phosphorus content in the fermentation liquid was lower than that of the control level when the concentration of EDTA reached 8mg/mL.5.Under the best phosphate solubilizing conditions,the solubilizing phosphor actinomycetes SY7 and SX3 secrete many organic acids in the process of dissolving calcium phosphate.In the process of dissolving calcium phosphate,2 strains of bacteria can secrete citric acid,lactic acid,oxalic acid,acetic acid,malic acid and succinic acid in the process of dissolving calcium phosphate,and the trend of the change of organic acid concentration is in accordance with the change trend of soluble phosphorus content in the fermentation liquid.6.The viability of 2 strains of phosphate actinomycetes were preliminarily identified and tested by culture test.The results showed that strain SY7 had strong antagonism to Fusarium moniliforme,Diplocarpon Rosae and F.graminearum,and strain SX3 has strong bacteriostasis effect against F.solani and F.oxysporium causing ginseng wilt,watermelon wilt and Cucumber wilt diseases.Both of strain SY7 and SX3 can produce iron carrier and secrete the indoloacetic acid?IAA?which can promote plant growth and culture test.The cultivation test verified that the growth and root development of maize plants could be promoted,and the content of soluble phosphorus in soil could be increased.