Production of Mannan from local isolates of Saccharomyces cerevisiae by autolysis

Abstract

The research was carried out in the laboratory of the National Commission for Biotechnology during the period (2019-2021) in order to extract mannan according to the autolysis method from three local isolates of Saccharomyces cerevisiae (SAC1,SAC2,SAC3) grown on two different media (YEPD: peptone dextrose yeast extract, SDB: Sabouraud Dextrose Broth), and studying the effect of acid treatment and heat treatment on the efficiency of the autolysis process. The three baker's yeast isolates were grown on YEPD medium and SDB medium to obtain the highest biomass of yeast where the yield ranged between 66.21 and 91.49 g and between 51.05 and 89.27 g on YEPD medium and SDB medium, respectively, and the isolate (SAC1) outperformed among the studied samples in terms of cost-effectiveness and was used for the purpose of multiplication and extracting mannan from it. Mannan was extracted from yeast according to the autolysis method, and the effect of temperature (40, 55 and 60) C and pH (5.9 and 4.4) on the efficiency of autolysis was studied. Statistical analysis showed a significant effect of temperature and pH change on the autolysis efficiency, which was reflected in a high yield of the percentage of protein and the resulting dry matter on the decomposition of the yeast wall (P < 0.05). The highest yields were obtained from the autolysis products at 60°C and pH 4.4. The optimum conditions for autolysis were applied to extract mannan, and the percentage of extracted mannan was 81.38 and 77.78% on YEPD medium and SDB medium, respectively.