PhoR/PhoP双组分系统对枯草芽胞杆菌NCD-2菌落形态和芽胞形成的影响

 双组分PhoR/PhoP是枯草芽胞杆菌中普遍存在的以低磷为信号的调控系统。前期研究发现,PhoR/PhoP双组分系统正调控枯草芽胞杆菌NCD-2菌株脂肽类抗生素fengycin的合成,本研究分析了PhoR/PhoP双组分系统对NCD-2菌株菌落形态和芽胞形成的影响。在有机磷培养基上,NCD-2野生型菌株可以降解有机磷并且形成表面褶皱、立体结构较强的菌落形态,而phoR或phoP基因突变子丧失了降解有机磷的能力,菌落表面光滑、平坦。phoR和phoP基因突变子的互补菌株恢复到了与野生型相似的解磷能力和菌落形态。在低磷和高磷培养基中比较了NCD-2野生型及其衍生菌株的生长及芽胞形成情况,结果表明,在高磷培养基中,NCD-2野生型及其衍生菌株的生长速率没有差异,但在低磷培养基中,phoR和phoP基因突变子的菌体生长速率显著降低。芽胞形成能力测定结果表明,在低磷培养基中,NCD-2野生型菌株的芽胞形成率较高,而phoR和phoP基因突变子的芽胞形成率显著降低;在高磷培养基中,NCD-2野生型及其衍生菌株芽胞形成率普遍较低并且无显著差异。RT-PCR分析显示, phoR和phoP的突变均显著降低了芽胞形成相关基因spo II GA的表达,相比感应激酶PhoR,调控因子PhoP对spo II GA基因的影响更显著。

The PhoR/PhoP two-component system regulates colony morphology and sporulation in Bacillus subtilis strain NCD-2

The PhoR/PhoP two-component system induced by low concentration phosphate is one of the important regulatory systems in Bacillus subtilis. It was reported that the PhoR/PhoP two-component system regulates the production of fengycin in B. subtilis strain NCD-2. In this study, the regulatory effect of PhoR/PhoP two-component system on the colony morphology and sporulation was determined. The results indicated strain NCD-2 was able to solubilize organic phosphorus and formed wrinkled and dimensional colonies on organic phosphorus medium while both the phoR and the phoP mutants lost the organic phosphorus solubilizing abilities and showed smooth and flat colonies. The growth and sporulation between wild type NCD-2 and its mutants were compared under high or low phosphate conditions. The results showed that both the phoR and phoP mutants decreased the growth under low phosphate condition, compared to strain NCD-2 while no difference was found among the strains in high phosphate medium. Under low phosphate condition, strain NCD-2 had significantly higher sporulation rate than the phoR and phoP mutants, but under high phosphate condition, all bacteria had low sporulation abilities and no significant differences were observed between strain NCD-2 and the phoR or phoP mutants. RT-qPCR assay indicated that phoR and phoP positively regulated the expression of sporulation associated gene spo II GA, and the regulation of PhoR on spo II GA expression was more intense than PhoP.