Biosynthetic activity study of Lactobacillus acidophilus lactic acid bacteria in the lactose fermentation of whey

The article presents a study into the effect of long-term, low-temperature (-80 and -150 °С) storage on the properties of Streptomyces lucensis RNCIM As-1743 and Streptomyces violaceus RNCIM As-1734 actinomycete collection strains acting as producers of glycosidase inhibitors. The titre (CFU in 1 cm3 of the initial inoculum) and the inhibitory activity of strains were determined with respect to pancr eatic α-amylase in the solutions obtained by Streptomyces culture on a corn starch hydrolysate. For Streptomyces, a high survival rate (91–100 %) was established after storage at temperatures of -80 and -150 °C using a 15 % glycerol solution in terms of a cryoprotector. Streptomyces violaceus strain was identified to be the most resistant to long-term storage at low temperatures. Its inhibitory activity turns to be completely retained after storage at temperatures of -80 and -150 °С. In Streptomyces violaceus strain, the maximum activity level of 2250±200 IU/cm3 for an inhibitor of pancreatic α-amylase is observed on the 1st day of subculture, while Streptomyces lucensis RNCIM As-1743 demonstrates the highest activity value on the 3rd day to reach a value of 3660±200 IU/cm3 following storage at a temperature of -80 °С. The studied Streptomyces strains are chromogenic. The most intense chromogenesis is noted during the culture of Streptomyces violaceus strain stored at a temperature of -150 °С. The cryopreservation of Streptomyces violaceus and Streptomyces lucensis actinomycete strains was established to provide high (107 –108 ) cell survival and preservation of their inhibitory activity at a high level when exposed to temperatures of -80 and -150 °С with a 15 % glycerol solution as a cryoprotector. Experimental data indicate the low-temperature storage method to be promising for Streptomyces lucensis and Streptomyces violaceus collection cultures. The authors declare no conflict of interests regarding the publication of this article.