枯草芽胞杆菌NCD-2中调控因子PhoP对fengycin合成的调控作用

Regulation of fengycin biosynthase by regulator PhoP in the Bacillus subtilis strain NCD-2

PhoR/PhoP双因子调控系统是枯草芽胞杆菌中一个重要的全局性调控系统,在低磷环境下,感应激酶PhoR自磷酸化,并且将获得的磷酸基团转移到调控因子PhoP上,从而激活PhoP的调控活性。为了明确调控因子PhoP对枯草芽胞杆菌NCD-2菌株中主要抑菌活性物质-fengycin合成能力的调控作用,本研究通过同源重组技术缺失突变NCD-2菌株中的phoP基因,拮抗活性测定结果表明,phoP基因缺失菌株显著降低了对立枯丝核菌的抑菌活性。通过快速蛋白质液相色谱(FPLC)技术比较了NCD-2菌株野生型及其phoP基因突变子fengycin的合成能力,结果证明,phoP基因突变菌株降低了fengycin的合成能力。对突变子进行phoP基因互补发现,互补phoP基因可使突变子的相关性状恢复到野生型菌株水平。以上结果证明,phoP基因对枯草芽胞杆菌NCD-2菌株中fengycin的合成具有正调控功能。

PhoR/PhoP two-component is a global regulatory system in Bacillus subtilis. Under the phosphate starvation condition, the sensor protein kinase PhoR self-phosphorylates and transfers its phosphate group to the regulator PhoP. The phosphorylated PhoP impresses or activates the expression of phosphate-regulated genes. With the purpose of clarifying the function of regulator PhoP on the fengycin production in B. subtilis NCD-2, the phoP was in-frameless deleted by homologous recombination. The testing showed that the phoP mutant decreased the antifungal ability against the growth of Rhizoctonia solani in vitro. The lipopeptides were extracted from strains NCD-2 wild type and phoP mutant, then analyzed by Fast Protein Liquid Chromatography （FPLC）. The results indicated that the production of fengycin, the major antifungal activity compound in strain NCD-2, was significantly decreased in the phoP mutant compared to that of strain NCD-2 wild type. All of these characteristics were restored by complementation of phoP gene in the phoP deletion mutant. It was confirmed that the phoP was a positively regulation factor for fengycin production in strain NCD-2.