Obtaining yeast mannoproteins with antimicrobial properties

Abstract

Introduction: Mannoproteins (MP) contained in the yeast cell wall (YCW) have high biological activity and possess several techno-functional properties. They are actively used in oenology, as a colloidal stabilizer and an inhibitor of the crystallization of potassium bitartrate, agriculture, as a feed additive for animals, the food industry, as an emulsifier. We obtained MP from Saccharomyces cerevisiae yeast and evaluated antimicrobial properties against Bacillus subtilis and Escherichia coli.

Methods: YCW was obtained by autolysis of 15% yeast suspension of S. cerevisiae for 24 h at the temperature of 55° C with the initial pH of 5.0 and mixing at 120 rpm. MP preparations from YCW were obtained in two ways, namely, thermal extraction at the temperature of 121° C and alkaline extraction. The precipitated protein was dried in a dehydrator and then crushed. After that, MP were tested in relation to two cultures of E. coli and B. subtilis by sowing on liquid and solid nutrient media, with the addition of MP preparation obtained by various methods and different concentrations.

Results: As a result of induced autolysis, YCW was obtained with a yield of 27%. The MP yield after thermal and alkaline extraction was 12.0 and 12.9%, respectively. In relation to E. coli, alkaline MP showed the inhibitory ability of 37% at the preparation concentration of 5% (m/v). The fraction obtained by thermal means demonstrated minimal antimicrobial activity (AA). Inhibition was 4% relative to the control sample at the preparation concentration of 3% (m/v). According to the experimental data obtained with respect to B. subtilis, AA of the alkaline (3% m/v) fraction was 80%. The thermal (5% m/v) fraction did not manifest AA, on the contrary, it acted as a catalyst for colony growth.

Conclusions: Mannoprotein obtained by alkaline extraction showed an inhibitory effect on the growth of B. subtilis and E. coli. The resulting preparation can be used as a feed additive to agriculture animals as an alternative to antibiotics. With proper cleaning, this preparation can be used in medicine and cosmetology. 

 

Keywords: mannoprotein, cell wall, yeast, Saccharomyces cerevisiae, antimicrobial properties