The aim of the work is to study the inhibitory activity of the Streptomyces lucensis VKPM Ac-1743 and Streptomyces violaceus VKPM Ac-1734 strains stored at –18 °C in a 15 % glycerol solution and in a 0.9 % sodium chloride solution.The object of the study was the actinomycete strains of S. lucensis VKPM Ac-1743 and S. violaceus VKPM Ac-1734 producers of glycosidase inhibitor, which is a micro-ingredient for creating products with a low glycemic index. The storage time was nine months. Bookmark storage was performed by flushing with a taped agar starchcontaining environment of Capek. For comparison, we studied the properties of cultures stored at +4 °C without cryoprotectant.Deep cultivation of Streptomyces strains was carried out in a periodic manner on a medium containing corn starch hydrolyzate under the Multitron incubator shaker (INFORS,Switzerland).Inhibitory activity was determined in inactivated native solutions by a colorimetric method with respect to pancreatic α-amylase, a test glycosidase involved in carbohydrate metabolism, and whose activity was chosen as a criterion for assessing the hypoglycemic action of the inhibitor. The proteinase activity of the inactivated native solution was determined by a modified method using a casein substrate.The experimental data were processed using the methods of mathematical statistics and Excel XP programs.As a result of the research, it was established that the actinomycete strains of S. lucensis and S. violaceus, the producers of glycosidase inhibitors, can maintain inhibitory activity during low-temperature storage for nine months.For the S. lucensis actinomycete strain, stored in a 15 % glycerol solution at – 18 °C, the maximum inhibitory activity is 48 hours in the biotechnological process and is (3686 ± 300) IU/cm3 native solution, and for theviolaceus strain – (3150 ± 200) IU/cm³of the native solution, respectively.For the strain of actinomycete S. lucensis, stored in 0.9 % sodium chloride solution at a temperature of – 18 °C, the maximum inhibitory activity accounts for 72 h of the biotechnological process and is (2600 ± 200) IU/cm³ of the native solution, and for the strain S. violaceus the maximum inhibitory activity accounts for 24 hours of the biotechnological process and is (3530 ± 200) IU/cm³ of the native solution.At a storage temperature of +4 °C, the inhibitory activity for the strain of actinomycete S. lucensis is (560 ± 20) IU/cm³of native solution, and for the strain of S. violaceus – (1747 ± 100) IU/cm³ of native solution, respectively. On the basis of the data obtained, it can be concluded that a temperature of –18 °C is preferred for long-term storage.During the cultivation of Streptomyces strains, proteinase activity ranged from (0,012 ± 0,001) U/cm³ to (0,072 ± 0,002) U/cm³.The obtained data can be applied in further studies to develop conditions for long-term storage of collection crops.
Nutritional value of cold-pressed rapeseed oil during long term storage as influenced by the type of packaging material, exposure to light & oxygen and storage temperature
