Determination the Optimum Conditions for β-glucan Production Extracted from Saccharomyces cerevisiae

Abstract

Β-glucan is a natural polysaccharide composed of a group of glucose monomers linked by beta glycoside bonds that yeasts can be synthesized. The effect of different temperatures, inoculum size, glucose concentration, yeast extract concentration, pH, and culture media on the β-glucan production from saccharomyces cerevisiae was studied. In addition, the dry weight of biomass containing β-glucan was measured. The results showed that the optimum conditions for β-glucan production were when the cells were grown at 30 ºc for 48 hours and pH = 7 with 10 % inoculum size, 2% glucose, and 0.1% yeast extract. Furthermore, the best culture medium for β-glucan production was yeast extract-glucose medium with a dry weight of glucan 2.5mg/5ml. In addition, this study aimed to determine the best method for β-glucan extraction with acceptable purity and concentration. Β-glucan was extracted using two methods autolysis and alkali-acids extraction. The dried and weighed crude β-glucan was 6 gm/l, and 8 gm/l for autolysis of yeast cells, and alkali-acids extraction, respectively. The analysis of glucan by FT-IR and HPLC showed that the method of extraction by autolysis of yeast cells was successful to obtain β-glucan without the presence of the α-glucan with a concentration of β-glucan 10.8mg/gm, while in the extraction by alkali-acid were obtained mixtures of α-glucan and β-glucan with the concentration of β-glucan 7.4 mg/gm. The current study revealed that the optimum conditions of β-glucan production and the best culture medium for β-glucan production was yeast extract-glucose medium and the best method for β-glucan extraction was autolysis extraction.