Stretton S, Marshall K C, Dawes I W, Goodman A E
School of Microbiology and Immunology, University of New South Wales, Sydney, Australia.
FEMS Microbiol Lett. 1996 Jun 15;140(1):37-42. doi: 10.1111/j.1574-6968.1996.tb08311.x.
Characterisation of two genes in Pseudomonas sp. S91 that are responsive to carbon dioxide is reported. These were identified by random transposon mutagenesis leading to fusion of the Escherichia coli lacZ reporter gene to the genes of interest. Expression of the genes' promoters was quantified by measuring the reporter gene product, beta-galactosidase. beta-Galactosidase synthesis was induced when cells were exposed to 10% CO2 on solid media or during growth in aqueous phase when the culture density was greater than 1 at 610 nm, in either rich or minimal media. Induction of beta-galactosidase synthesis was not due to: increased alkalinity, onset of stationary phase, build up of soluble metabolites in the culture supernatant, or cell density-dependent signalling. The CO2-inducible gene fusions were not induced by other environmental conditions that are known to stimulate global regulators of environmental gene expression. Benzoic acid (2 mM) induced beta-galactosidase synthesis in one of the mutants indicating the Co2 response may involve the intracellular CO2 partial pressure/bicarbonate ion concentration/pH equilibrium.
报道了假单胞菌属S91中两个对二氧化碳有反应的基因的特性。这些基因是通过随机转座子诱变鉴定出来的，该诱变导致大肠杆菌lacZ报告基因与目标基因融合。通过测量报告基因产物β-半乳糖苷酶来定量基因启动子的表达。当细胞在固体培养基上暴露于10%二氧化碳时，或在水相中生长且培养密度在610nm处大于1时，无论是在丰富培养基还是基本培养基中，β-半乳糖苷酶的合成都会被诱导。β-半乳糖苷酶合成的诱导不是由于：碱度增加、稳定期开始、培养上清液中可溶性代谢物的积累或细胞密度依赖性信号传导。已知刺激环境基因表达全局调节因子的其他环境条件不会诱导二氧化碳诱导型基因融合。苯甲酸（2mM）在其中一个突变体中诱导了β-半乳糖苷酶的合成，这表明二氧化碳反应可能涉及细胞内二氧化碳分压/碳酸氢根离子浓度/ pH平衡。
