一株高效解磷肠膜明串珠菌的分离鉴定及解磷能力研究

Isolation and identification of a phosphate solubilizing bacterium Leuconostoc mesenteroides and its ability to dissolve phosphorus

【背景】植物根际土壤含有多种溶磷微生物,但是具有溶磷能力的肠膜明串珠菌未见报道。【目的】从脐橙根际土壤分离高效解磷菌,研究其解磷应用。【方法】通过初筛和复筛从23株菌中筛选解磷能力较强的菌株,同时采用钼蓝比色法测定磷含量。通过测定发酵液中小分子有机酸含量、磷酸酯酶酶活及pH值的变化,探究菌株的解磷机理。【结果】经过筛选得到9株具有一定解磷能力的菌株。通过菌种16S rRNA基因序列分析和生理生化实验确定其中一株菌为肠膜明串珠菌,命名为肠膜明串珠菌G7。培养基初始pH6.0、碳源为葡萄糖、氮源为硫酸铵时G7的解磷能力较佳。G7发酵过程中产生大量有机酸,而其酸性磷酸酯酶活性高于碱性磷酸酯酶。【结论】碳源、氮源以及初始pH值都能影响G7的解磷能力,其解磷能力主要缘于在发酵过程中产生了大量小分子有机酸,关于G7的解磷机理还需要更深入的研究。

[Background] Many microorganisms from plant rhizosphere soil have phosphate solubilizing ability, while phosphate solubilizing Leuconostoc mesenteroides have not been reported. [Objective] To isolate and identify efficient phosphate solubilizing bacteria from navel orange rhizosphere soil and investigate the application in phosphorus release. [Methods] Transparent circle assay was used to preliminarily screen the phosphate solubilizing bacteria. After secondary screening, soluble-P in the culture medium was determined by molybdate blue colorimetric method. Different parameters were determined to explore the phosphate solubilizing mechanism of one strain. The phosphate solubilizing mechanism of the strain was explored by measuring the content of low-molecular-weight organic acids in the fermentation broth, the enzyme activity of phosphatase and its pH value. [Results] Nine phosphate solubilizing strains out of 23 candidates were obtained after two step selection. Based on 16S rRNA gene sequence analysis and physiological and biochemical chanterization, a strain was obtained and named Leuconostoc mesenteroides G7. The optimal phosphate solubilizing conditions of the strain G7 were as follows： the initial pH was 6.0, the carbon source was glucose, and the nitrogen source was ammonium sulfate. G7 produced a mass of organic acids, and its acid phosphatase activity was higher than that of alkaline phosphatase. [Conclusion] Carbon source, nitrogen source and initial pH can influence the phosphate solubilizing ability of the strain G7. The phosphate solubilizing ability of G7 is mainly due to its large number of low-molecule organic acids produced during fermentation. The mechanism of phosphate solubilizing ability need to be researched thoroughly.