THE INFLUENCE OF THE ORGANIC NITROGEN SOURCE CONTENT ON THE ACTIVITY OF CHOLESTEROL OXIDASE PRODUCER

494 Volume 5, Issue 10: Special Issue (EJAR) ISSN: 2181-2020 MPHAPP THE 6TH INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE “MODERN PHARMACEUTICS: ACTUAL PROBLEMS AND PROSPECTS” TASHKENT, OCTOBER 17, 2025 in-academy.uz THE INFLUENCE OF THE ORGANIC NITROGEN SOURCE CONTENT ON THE ACTIVITY OF CHOLESTEROL OXIDASE PRODUCER Shpachuk A.Yu. Ponomarev N.D. Khryachkova E.N. Kolodyazhnaya V.A. St. Petersburg State Chemical Pharmaceutical University, St. Petersburg, Russian Federation e-mail: [email protected] https://doi.org/10.5281/zenodo.17343154 Background: Cholesterol oxidase (CHO) is an enzyme from the oxidoreductase class that catalyzes the conversion of cholesterol to cholest-4-en-3-one and hydrogen peroxide. It can be used in test systems for determining blood cholesterol levels or as a catalyst in the synthesis of biologically active derivatives of cholesterol. This enzyme is obtained only through microbial synthesis, during which the selection of an optimal nutrient medium (NM) in general and the optimal content of the organic nitrogen source, in particular, remains a very relevant issue. Aim: To analyze the influence of the content of the organic nitrogen source (yeast autolysate) on the CHO activity in the mycelium of Streptomyces lavendulae (the producer bacterium). Materials and methods: The producer culture was stored in a refrigerator at 2-8°C on slanted agar, from where a sufficient amount was transferred under aseptic conditions to a 750 ml shake flask (volume of sterile NM – 150 ml). The producer was then cultivated for 47-48 hours at a temperature of 28°C and a shaking speed of 210 min⁻¹. The producer's activity was measured using the Richmond method (spectrophotometrically by the increase in optical density per minute of the catalyzed reaction). The Plackett-Burman design (PBD) was used to assess the significance of the influence of various factors on the cultivation results (including the factor of the organic nitrogen source content). Results: The PBD showed that the factor of yeast autolysate content is significant for CHO activity in the mycelium. However, its excessive amount has a detrimental effect on the producer (which is probably associated with the accumulation of an excess amount of ammonium in the cultural liquid). Therefore, experiments were conducted to find the optimal content of the organic nitrogen source. As can be seen from the presented graph, the optimum is likely somewhere between 0.7 and 0.8 g of yeast autolysate per 150 ml of NM. Conclusions: Thus, an understanding of the nature of the influence of the organic nitrogen source content on the CHO activity in the Streptomyces lavendulae mycelium has been obtained. 495 Volume 5, Issue 10: Special Issue (EJAR) ISSN: 2181-2020 MPHAPP THE 6TH INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE “MODERN PHARMACEUTICS: ACTUAL PROBLEMS AND PROSPECTS” TASHKENT, OCTOBER 17, 2025 in-academy.uz Furthermore, data providing an approximate idea of the optimal enzyme content has been obtained. In the future, this will help in scaling up the technology to industrial conditions.