Physiological analysis of the expression of the styrene degradation gene cluster in Pseudomonas fluorescens ST

• Published in: Applied and environmental microbiology Vol. 66; no. 4; pp. 1305 - 1310
• Main Authors: SANTOS, P. M, BLATNY, J. M, DI BARTOLO, I, VALLA, S, ZENNARO, E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.04.2000
• Subjects: acetate; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; BIODEGRADATION; Biodegradation, Environmental; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Carbon; Carbon - metabolism; ENVIRONMENTAL SCIENCES; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; GENE OPERONS; GENE REGULATION; Genes; Genes, Bacterial; Genetics; Genetics and Molecular Biology; GROWTH; Lac Operon; lactate; Microbiology; Mission oriented research; Multigene Family; Operon; Plasmid pPR9TT; Promoter Regions, Genetic; PSEUDOMONAS; Pseudomonas fluorescens; Pseudomonas fluorescens - genetics; Pseudomonas fluorescens - growth & development; Pseudomonas fluorescens - metabolism; PstyA operon; Recombinant Fusion Proteins; REMEDIAL ACTION; styA gene; styR gene; STYRENE; Styrene - metabolism; styrene monooxygenase; styS gene; stySR operon; succinate; Succinic acid; Pseudomonadales; Biodegradation; Gene cluster; Induction; Toxicity; Pseudomonas fluorescens; Gene expression; Carbon; Pollutant; Regulation(control); Gene; Nutrient source; Styrene; Microorganism culture; Bacteria; Pseudomonadaceae; Catabolic repression
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.66.4.1305-1310.2000

The effects of different carbon sources on expression of the styrene catabolism genes in Pseudomonas fluorescens ST were analyzed by using a promoter probe vector, pPR9TT, which contains transcription terminators upstream and downstream of the beta-galactosidase reporter system. Expression of the promoter of the stySR operon, which codes for the styrene two-component regulatory system, was found to be constitutive and not subject to catabolite repression. This was confirmed by the results of an analysis of the stySR transcript in P. fluorescens ST cells grown on different carbon sources. The promoter of the operon of the upper pathway, designated PstyA, was induced by styrene and repressed to different extents by organic acids or carbohydrates. In particular, cells grown on succinate or lactate in the presence of styrene started to exhibit beta-galactosidase activity during the mid-exponential growth phase, before the preferred carbon sources were depleted, indicating that there is a threshold succinate and lactate concentration which allows induction of styrene catabolic genes. In contrast, cells grown on glucose, acetate, or glutamate and styrene exhibited a diauxic growth curve, and beta-galactosidase activity was detected only after the end of the exponential growth phase. In each experiment the reliability of the reporter system constructed was verified by comparing the beta-galactosidase activity and the activity of the styrene monooxygenase encoded by the first gene of the styrene catabolic operon.