Bacteria from the genus Streptomyces are known for production of variety of secondary metabolites. Steptomyces species also serve as excellent host for production of heterologous secondary metabolites and a number of gene tools have been developed. The aim of this study was to insert two different plasmid vectors into the engineered strain of Streptomyces rimosus, which contains 145 kbp deletion encoding two main antibiotics oxytetracicline and rimocidine, which represent excellent heterologous host for production of diverse metabolites. Polyunsaturated fatty acids (PUFAs) play a crucial role in various physiological and paraphysiological processes in the human body. Among them, omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), hold a prominent position. These acids are associated with the prevention and treatment of cardiovascular diseases, obesity, and diabetes. In the study, biosynthetic gene cluster was used for the synthesis of polyunsaturated fatty acids. The cluster was composed of three genes: pfa1, pfa2, and pfa3. This pathway originates from the myxobacterium Aetherobacter fasciculatus. The biosynthetic gene cluster encodes a multifunctional enzyme catalysing synthesis of the unsaturated fatty acids such as EPA and DHA. Two plasmid vectors were used pAB04ErmE*PUFA and pAB04ErmE*PUFA-ppt. Both vectors used in the study carry gene cluster from the myxobacterium A. fasciculatus, encoding PUFAs. Additionally, the pAB04ErmE*PUFA-ppt plasmid also contains a gene for phosphopantetheinyl transferase, which is expected to enhance the synthesis of PUFAs. Vectors were constructed and transferred into the bacterium S. rimosus OTC 145. The S. rimosus strains containing the genes pfa1, pfa2 and pfa3 had the ability to produce DHA. The final concentration of DHA ranged from 1-4 mg/L. By a simple media optimization, such as adjusting the concentrations of carbon, nitrogen, phosphorus sources, and vegetable oil, a DHA titer of 21.03 mg/L was achieved, representing a 17-fold increase compared to the baseline production medium GOTC-P.
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