Abstract
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.
Highlights
Actinobacteria of the Streptomyces genus manifest themselves as producers of more than half of the most common biologically active compounds applied in medicine, veterinary, agriculture and other industries
The inhibitory activity of cells survived after storage was determined in the obtained solutions by culturing Streptomyces lucensis and Streptomyces violaceus using the colorimetric method in reference to pancreatic amylase
Previous studies have proved the low temperature storage of Streptomyces to cause no adverse effect on the viability and inhibitory activity of cultures
Summary
Actinobacteria of the Streptomyces genus manifest themselves as producers of more than half of the most common biologically active compounds applied in medicine, veterinary, agriculture and other industries. The first type of protectors (glycerin and DMSO) have been shown to be more effective and applicable for a wide range of bacteria [5] In this case, the protective action of glycerin is explained by its prevention of excessive salt concentration levels causing a violation of biochemical processes in microorganism cells during freezing [3]. The present study is aimed at the effect of low temperatures (-80 and -150 °С) on the viability of Streptomyces lucensis RNCIM As-1743 and Streptomyces violaceus RNCIM As-1734 actinomycetes and their preservation of inhibitory activity during storage. The inhibitory activity of cells survived after storage was determined in the obtained solutions by culturing Streptomyces lucensis and Streptomyces violaceus using the colorimetric method in reference to pancreatic amylase (test enzyme). Statistical processing data on inhibitory activity and viability was performed using the Microsoft Office Excel 2010
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