ИСТИНА

6S RNA is a small non-coding RNA that has a conserved secondary structure similar to DNA in an open complex with RNA polymerase. It competes with DNA for binding to the enzyme and acts as a global transcription regulator in bacteria cells. It is known that Bacillus subtilis cells have two 6S RNAs, which are 6S-1 and 6S-2. The hypothesis that small non-coding RNAs affect and participate in the regulation of surfactin biosynthesis in B. subtilis can be made based on some scientific papers results. Surfactin is a well-known and highly sought-after biological surfactant. Microbiological synthesis is the only way for producing significant amounts of surfactin. The knockout of the 6S-1 and 6S-2 genes in B. subtilis does not cause fatal consequences for the cell. Therefore, studying the role of 6S RNA in the metabolic pathway of surfactin could lead to the development of a new method for increasing the yield of surfactin formed by organisms. The object of this research is B. subtilis NCIB 3610 which is natural strain of B. subtilis. It has been observed that deletion of the 6S-1 RNA gene leads to the increase of the level of mRNA for all the genes of srfA operon, which encodes four subunits of surfactin synthase, during the late stationary phase of growth. To evaluate the effectiveness of surfactin biosynthesis in bacterial cells, the spectrophotometric method based on the disruption of the complex between a pH indicator, bromothymol blue, and a cationic surfactant, cetylpyridinium chloride, when a surfactin solution is added to it, was optimized We also used reversed-phase high-performance liquid chromatography (HPLC) to validate the results. Despite the increase in transcription levels of the surfactin synthase subunits genes, deletion of the 6S-1 RNA gene did not lead to increase of surfactin yield produced by B. subtilis NCIB 3610. To explain this result, we investigated the effect of 6S-1 RNA gene deletion on the transcription efficiency of genes that have an indirect Influence on surfactin biosynthesis in B. subtilis. For instance, these genes encode synthetases of fatty acids and amino acids that are the parts of surfactin molecule, or synthetases of polyketides and exopolysaccharides that compete with surfactin synthetase for cellular resources. It has been observed that deletion of the 6S-1 RNA gene led to a significant increase in the expression of rocG and glnA genes. These genes are responsible for glutamine acid catabolism which is the first amino acid in the surfactin peptide fragment. So, a decrease in glutamine acid level inside the cell could negatively affect the yield of surfactin, leading to a lack of increased efficiency in mutant cells. Similar studies are being conducted on 6S-2 RNA. This work was supported by the Russian Science Foundation (project No 24-24-00193)