Influence of redox processes on the antioxidant activity of the symbiotic starter biomass

The biological system of the microbial antioxidant protection is a subject of a certain level of the physiological oxidative process. To prevent oxidation, a regulator of intracellular metabolism, tripeptide glutathione, is accumulated in cells. Glutathione is very important for the antioxidant response and maintenance of intracellular redox potential. Its role in several metabolic adaptive symbiotic processes of yeasts and lactic acid bacteria is not completely elucidated and is of scientific and practical interest. Glycine is a component of the polypeptide chain and substances that form the primary structure of glutathione. The aim of this study was to determine an effect of the redox processes on the antioxidant activity through regulation of the level of the glutathione constituent, glycine, in a nutrient medium to obtain the microbial biomass of the multicomponent starter culture. As a result of the performed investigations, a direct dependence between the antioxidant activity calculated by the coulometric method and concentration of glycine introduced into the nutrient medium was determined. It has been established that addition of 0.2–0.8% of glycine leads to a decrease in the redox potential. The results reflected in this publication show that the process of the development of aerobic microorganisms in the presence of reducing substances occurs quite actively. The number of yeasts increased from 1.6· 104 to 3.6· 105 CFU/g during 24-hour incubation. An increase in glycine from 0.5 to 0.8% enhanced the development of both anaerobic and aerobic microorganisms. It has been found that an increase in the glycine concentration from 0.8% to 1.5% shifted the process toward the oxidative metabolism; an amount of reduced glutathione in the culture liquid increased practically twofold, while the concentration of oxidized glutathione in the test sample was in a range of 0 to 5%. This allows regarding glutathione as a potential regulator of the redox processes and antioxidant activity of biomass of lactic acid bacteria and yeasts.