Identification of a strain of Streptomyces from Lop Nur Salt Lake and the inhibitory effect of its metabolites on tyrosinase activity and melanin production. Tyrosinase (EC1.14.18.1, tyrosinase), also known as polyphenol oxidase, is a key enzyme in the biosynthesis of melanin in animals, plants, and microorganisms. Its expression activity determines the rate and quantity of melanin production. Tyrosinase inhibitors have great application prospects in cosmetics, fruit and vegetable preservation, biopesticides, and the treatment of melanin metabolism diseases. At present, tyrosinase inhibitors are mainly obtained through natural product extraction or chemical synthesis. Extreme environmental microorganisms have formed special gene types and physiological mechanisms in environments where other organisms cannot survive, such as strong acids, strong bases, and strong radiation. They can produce structurally novel and biologically active secondary metabolites, providing new ideas for the screening of tyrosinase inhibitors. The research object of this article is a strain of Streptomyces 89-2-2 isolated from the second largest saltwater lake in China, Lop Nur in Xinjiang. It has been identified as a strain of Streptomyces setonii. Fermentation of Streptomyces sp. Z-L-22 can produce antibacterial active substances. It has been discovered that the bacterial cells of Streptomyces coelicolor and their produced phosphodiesterases can degrade organophosphate insecticides. At present, there are no reports on the production of tyrosinase inhibitors and melanin synthesis inhibitors by Streptomyces coelicolor. This experiment investigates the inhibitory activity of Streptomyces setonii 89-2-2 metabolites on tyrosinase activity and melanin synthesis, in order to further explore the unique biological activity potential of microorganisms in extreme environments and lay the foundation for the development of urgently needed natural melanin synthesis inhibitors and their lead compounds in the fields of medicine, cosmetics, etc.

 

The optimal salt concentration for strain 89-2-2 is 5%, and it belongs to moderately halophilic Streptomyces. Based on morphological characteristics, culture characteristics, physiological and biochemical properties, cell wall chemical composition, and 16SrRNA gene sequence analysis, strain 89-2-2 was preliminarily identified as Streptomyces setonii. The IC50 of the extract of Streptomyces setonii 89-2-2 metabolite for in vitro mushroom tyrosinase diphenolase activity was 0.478mg/mL. Within the concentration range of 100-1000 μ g/mL, the extract of strain 89-2-2 had no significant effect on the proliferation of mouse melanoma B16 cells, but could significantly inhibit intracellular tyrosinase activity and effectively reduce intracellular melanin content; After 48 hours of treatment with 1000 μ g/mL extract, B16 cells showed a 48% decrease in intracellular tyrosinase activity and a 31% decrease in melanin content. The detection results of metabolomics show that S The differential metabolites produced before and after optimizing the fermentation conditions of Setonii 89-2-2 are mainly vitamin compounds, aromatic compounds, and carboxylic acid compounds. Previous reports have shown that all three types of substances have the ability to inhibit tyrosinase activity. It can be seen that S. setonii 89-2-2 is a promising material with development potential for producing tyrosinase inhibitors and melanin synthesis inhibitors.