玉米根际溶磷放线菌的溶磷特性及机理研究

Increasingly exhausted phosphate rock resources and activation of invalid phosphorus element in soil are important problem needed to be solved in resources and fertilizer sciences. Actinomycetes are highly concerned for production of many kinds of active substances and their growth-promoting and disease-resistant effects.But the resources of phosphate solubilizing actinomycetes and the mechanism of phosphate solubilization are investigated very little, resulting in limitation of their applications. In order to confirm the best phosphate solubilizing condition and polyphosphate synthesis conditions and the relationship of among phosphate solubilizing ability, polyphosphate synthesis and dynamic expression of metabolites, investigate the metabolic markers participating in phosphate solubilization, and reveal the optimal metabolic model, mechanism of phosphate solubilization and regulation pattern of external factors to phosphate solubilization effect of actinomycetes, we screen phosphate solubilizing actinomycetes from maize rhizosphere soil, confirm the utilization ability and best metabolic model of screened strains to insoluble phosphorus under different culture conditions by cell phenotype chip technology, and determine the dynamic expression spectrum of metabolites of phosphate solubilizing actinomycetes in the optimal culture conditions using metabonomics method based on LC-MS. The present stdudy aims to develop resources of phosphate solubilizing actinomycetes, deeply understand the mechanism of phosphate solubilization, and provide the material and theoretical basis for the development and application of slow-release bio-phosphate fertilizer and the activation of invalid phosphorus element in soil.

磷矿资源日渐枯竭和土壤无效磷素的活化是资源学和肥料学急需解决的重要问题。放线菌因产多种活性物质和抗病促生等多重功效而备受关注，但对溶磷放线菌资源和溶磷机理的研究甚少，限制了溶磷放线菌的应用。本课题（1）从玉米根际土壤中筛选溶磷放线菌，构建溶磷放线菌资源库（2）利用细胞表型芯片技术，确定不同培养条件下，菌株对难溶性磷的利用能力和最佳代谢模式（3）利用基于LC-MS的代谢组学方法，测定溶磷放线菌在最适培养条件下的代谢物动态表达谱。探明菌株最佳溶磷条件和多聚磷酸盐合成条件；最佳培养条件下菌株溶磷能力、多聚磷酸盐合成与代谢物动态表达之间的关系，明确参与放线菌溶磷的代谢标志物，从代谢物层面上揭示放线菌的最佳代谢模式和溶磷机制及外界因素对溶磷作用的调节规律。本研究旨在开发溶磷放线菌资源，深入认识放线菌溶磷的机制，为缓释生物磷肥的开发、应用和解决土壤无效磷活化的实际问题提供材料和理论依据。

磷矿资源日渐枯竭和土壤无效磷素的活化是资源学和肥料学急需解决的重要问题。放线菌因产多种活性物质和抗病促生等多重功效而备受关注，但对溶磷放线菌资源和溶磷机理的研究甚少，限制了溶磷放线菌的应用。本课题（1）对吉林省主要玉米产区非根际和根际土壤放线菌资源的组成及其丰度进行测定，结果表明非根际土壤放线菌由68个属组成，根际土壤放线菌由73个属组成，非根际土壤和根际土壤放线菌在物种组成和丰度上具有较大的差别；从玉米根际土壤中筛选出63株放线菌，其中21株放线菌具有溶磷的功能，并对四株具有较强溶磷功能的放线菌进行鉴定，鉴定结果为链霉菌属和小单孢菌属的放线菌；（2）利用细胞表型芯片技术，摸索链霉菌属菌株47和小单孢菌属菌株SX31的最佳溶磷条件，结果与正交试验结果一致，表明细胞表型芯片技术可以用于溶磷放线菌的最佳溶磷条件的筛选；链霉菌属菌株47的最佳溶磷碳源和氮源为葡萄糖和硝酸钾，小单孢菌属菌株SX31的最佳溶磷碳源和氮源为葡萄糖和硫酸铵；在菌株溶磷的同时，还具有聚磷的功能，以备缺磷时作为磷源；最佳溶磷条件下，随着Ca2+添加浓度的增加，发酵液中可溶磷含量降低，随着EDTA添加溶度的增加，发酵液中可溶磷含量增加；溶磷放线菌菌株47和SX31除具有溶磷功能，还具有产铁载体和抑制土传病害病原菌的功能；（3）采用NMR技术、HPLC法研究溶磷放线菌菌株47细胞内和细胞外代谢物，菌株SX31胞外代谢物，结果表明：无论是胞外代谢物和胞内代谢物，有机酸是溶磷代谢标志物；色谱分离法获得的代谢产物——铁载体也具有螯合钙离子的磷増溶功能，不同放线菌菌株产铁载体的类型不同；磷酸酶是菌株47和SX31具有矿化有机磷化合物功能的标志物；（4）溶磷放线菌分泌有机酸溶解难溶性磷化合物，并通过有机酸和铁载体等代谢物螯合钙离子，促进难溶性磷化合物溶解。