Sacherer P, Défago G, Haas D
Department of Plant Sciences/Phytomedicine, Eidgenössische Technische Hochschule, Zurich, Switzerland.
FEMS Microbiol Lett. 1994 Feb 15;116(2):155-60. doi: 10.1111/j.1574-6968.1994.tb06694.x.
Pseudomonas fluorescens strain CHA0 protects plants from various root diseases. Antibiotic metabolites synthesized by this strain play an important role in disease suppression; their production is mediated by the global activator gene gacA. Here we show by complementation that the gacA gene is also essential for the expression of two extracellular enzymes in P. fluorescens CHA0: phospholipase C and a 47-kDa metalloprotease. In contrast, the production of another exoenzyme, lipase, is not regulated by the gacA gene. Protease, phospholipase and antibiotics of P. fluorescens are all known to be optimally produced at the end of exponential growth; thus, the gacA gene appears to be a general stationary-phase regulator.
荧光假单胞菌CHA0菌株可保护植物免受多种根部疾病的侵害。该菌株合成的抗生素代谢产物在病害抑制中发挥着重要作用；其产生由全局激活基因gacA介导。在此我们通过互补实验表明，gacA基因对于荧光假单胞菌CHA0中两种胞外酶的表达也是必不可少的：磷脂酶C和一种47 kDa的金属蛋白酶。相比之下，另一种胞外酶脂肪酶的产生不受gacA基因调控。荧光假单胞菌的蛋白酶、磷脂酶和抗生素均已知在指数生长末期产量最佳；因此，gacA基因似乎是一种通用的稳定期调节因子。
