影响甘蔗内生成团泛菌XD20生长和促生特性的因子分析

Factors analysis on endophytic Pantoea agglomerans XD20 affecting growth and growth-promoting characteristics of sugarcane

【目的】探讨环境因子对甘蔗内生成团泛菌(Pantoea agglomerans)XD20生长及促生特性的影响,为该菌的进一步开发应用提供参考。【方法】检测不同pH、氯化钠浓度、重金属、化学试剂及铁离子浓度、碳源、氨基酸及碳氮比对菌株XD20生长、嗜铁性能和溶磷性能的影响,并采用正交设计对碳源、氮源、氯化钠浓度进行优化筛选。【结果】菌株XD20适宜生长的pH在7左右,超过4%的氯化钠浓度会抑制其生长;菌株XD20具有一定的重金属耐受性,可在Mn7+、Cr6+浓度为5~400 mg/L范围内生长;以MSA作为基础培养基,当铁离子浓度为0~10μmol/L时,该菌的相对嗜铁量随铁离子浓度升高而升高,当铁离子浓度超过10μmol/L时,其相对嗜铁量含量呈降低趋势。以柠檬酸为碳源、脯氨酸为氮源、碳氮比为3∶1时,有利于菌株XD20嗜铁素的分泌。不同碳源对菌株生长和溶磷性能的影响结果表明,有利于该菌生长的碳源排序为甘油>葡萄糖>柠檬酸>蔗糖>苹果酸;正交试验结果表明,供试菌株XD20生长量最大的碳源、氮源和氯化钠浓度分别为0.1%柠檬酸、0.5 g/L硫酸铵和4%氯化钠;影响供试菌溶磷能力的因子顺序为钠离子浓度>碳源>氮源,菌株XD20溶磷量最大时的培养条件与其生长量最大时的培养条件一致。【结论】甘蔗内生固氮菌株XD20具有较好的环境耐受性,铁离子浓度会影响其生长量和嗜铁量。以柠檬酸为碳源、脯氨酸为氮源、碳氮比为3∶1时,有利于菌株XD20嗜铁素的分泌。0.1%柠檬酸、0.5 g/L硫酸铵和4%氯化钠的培养条件对其生长和溶磷特性的效果最好。

【Objective】The effects of environment factors on the growth and growth-promoting characteristics of the endogenous Pantoea agglomerans XD20 from sugarcane were studied to provide a reference for the further development and application of the strain.【Method】This study tested the growth,siderophore,and phosphorus dissolving capacity of P.agglomerans XD20 under different pH values,sodium chloride concentrations,heavy metals,chemical reagents and iron ion concentrations,carbon sources,exogenous amino acids,and carbon-nitrogen ratios.Orthogonal design was used to optimize the phosphorus dissolving from carbon source,nitrogen source and sodium chloride concentration.【Result】The suitable pH for the growth of XD20 was about 7.More than 4%sodium chloridecould inhibit the growth of the bacteria.XD20 had a certain tolerance to heavy metals and could grow in the range of Mn^7+and Cr^6+concentration from 5 to 400 mg/L.MSA was used as the basic medium.When the concentration of iron ion was in the range of 0-10μmol/L,the relative siderophore content of the bacteria increased with the increase of iron ion concentration.However,when the concentration of iron ion was more than 10μmol/L,the relative siderophore content of the bacteria tended to decrease.When citric acid was added as the carbon source,proline as the nitrogen source,and the ratio of carbon to nitrogen was 3∶1,it was beneficial to the secretion of XD20 siderophore.The effects of different nitrogen sourceson the growth and phosphorus dissolution performance of the strain showed that the suitable carbon source for the growth of the bacteria was glycerol>glucose>citric acid>sucrose>malic acid.The results of the orthogonal test showed that the concentration of carbon source,nitrogen source and sodium chloride with the largest growth of XD20 was 0.1%citric acid,0.5 g/L ammonium sulfate and 4%sodium chloride,respectively.The order of the factors influencing the capacity of phosphate solubilization was sodium ion concentration>carbon source>nitrogen source.The culture conditions of the strain XD20 with the largest phosphate solubilization were the same as the largest growth.【Conclusion】Sugarcane endogenous nitrogen-fixing XD20 has good environmental tolerance,and iron ion concentration can affect its growth and siderophore.When citric acid is used as carbon source,proline as nitrogen source and the ratio of carbon to nitrogen is 3:1,it is beneficial to the siderophore secretion of XD20.The culture conditions of 0.1%citric acid,0.5 g/L ammonium sulfate and 4%sodium chloride have the best effects on its growth and phosphorus solubility.