一株柠条内生解磷菌的分离鉴定及实时荧光定量PCR检测

Isolation,identification,real-time PCR investigation of an endophytic phosphatesolubilizing bacteria from Caragana korshinskii Kom. roots

结合形态观察与16S rDNA序列测定对柠条根系内分离筛选得到的解磷细菌C9进行鉴定,Blast比对结果表明C9为泛菌(Pantoea vagans)。在无机磷液体培养基培养条件下,用钼锑抗比色法研究它的解磷能力。结果表明,随着时间的延长,培养液中速效磷含量逐渐增加到4.45mg/L,溶液pH可降至4.2。进一步利用实时荧光定量PCR检测柠条根系中、柠条根际土壤与柠条根围土壤中该细菌存在的相对基因拷贝数,结果发现该基因在3种样品中的数量为:柠条根系>柠条根际土壤>柠条根围土壤,表明泛菌解磷细菌能聚集生长在柠条根系内,随着与根系接触距离的增加而呈逐级递减趋势。

The microbiota colonizing the rhizophere （immediately surrounding the root ） and the endophytic microbiota （within the root） contribute to plant growth, productivity and phytoremediation. The microbiota inhibiting the rhizosphere can both benefit and undermine the plant health, whereas mutualistic andophytic microbiota may provide physiologically accessible nutrients and phytohormones to improve the plant growth, or help the plant withstand salt and drought. In this study, one phosphate-solubilizing bacterium C9 was isolated from within the root system of Caragana Korshinskii Kom. It was identificated by morphology and 16S rDNA sequencing. Using BLAST software, C9 was identified as Pantoea. The phosphate-solubilizing capacity of C9 was assayed by molydenum-antimony-D-iso-aseorbie-aeid-eolorimetry （MADAC） in inorganic phosphorus liquid culture. The results showed that the available phosphorus content in culture increased to 4.45mg/L and the pH value dropped to 4.22. These data indicate that the strain C9 from Caragana Korshinskii Kom. root system is able to utilize the insoluble phosphate and transform insoluble phosphorus into available form for the plants. At the same time, the possible relationship among pH level and phosphate dissolving ability was discussed. Futhermore, real-time PCR method was developed for quantifying gene copy number of C9 in roots and soil. PCR results demonstrated that the copy number of C9 follows the sequence of Caragana Korshinskii Kom. root 〉 rhizosphere soil 〉 soil around rhizosphere Results indicate that Caragana Korshinskii Kom. exertspositive effects on the existent environment of C9 and helps improve salinity-alkalinity ecological environment gradually