Streptomyces rimosus is one of the most researched industrially important streptomycetes. It is known primarily as the manufacturer of oxytetracycline. In order to optimize the metabolic pathway to raise the yields of secondary metabolites, it is essential to know how to regulate the genes involved in these pathways. The ethylmalonyl-CoA pathway allows bacteria to grow on acetate as the sole carbon source, and the genes for this pathway together with the tetR gene are found in the emc operon. The role of regulatory protein TetR in this pathway is in some bacteria already known, as it regulates expression of the ccr gene. In the scope of the master's thesis we tested the role of tetR, which is located in the emc operon. We overexpressed tetR and tested whether acetate has an effect on the expression of this gene. In the first part of the thesis we evaluated the activities of PermE*, PoxyI, Phs and Ptg promoters. The tetR gene under the control of PermE* promoter showed the highes expression. Next, we cloned the tetR gene into the integrative vector pAB15 and transformed it into S. rimosus carrying xylE reporter gene under the control of Pemc from the bacteria Streptomyces rimosus and Streptomyces tsukobaensis. Transformed cells were grown in TSB and GOTC medium. We investigated the influence of TetR on Pemc expression in the presence and absence of acetate in the media. No difference was observed in the activity of Pemc in the presence and absence of TetR except for the slight positive increase in the activity of Pemc promoters in strains with tetR that were grown with acetate. However, this diference was not statistically significant.
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