Extraction And Application Of RNA, β-(1,3)-D-glucan And Protein From Beer Yeast

Beer yeast is abundant in nutrients: 48.8% of protein and high content of firstly limiting amino acids-lysine; 29% ofβ-(1,3)-D-glucan which is the most efficient anti-cancer polysaccharides compounds in biopolysaccharides; 2.67~10.0% of RNA that is important in medical, food, cosmetic and agriculture et al. China is the biggest beer producer, and more than 100 thousand tons dry beer yeast is produced at the same time. Making use of waste beer yeast to produce useful substances can not only decrease environmental pollution but also increase tremendous economical and social benefit by extending the beer industry. In this paper, technology of extraction, isolation and purification of RNA,β-(1,3)-D-glucan and protein from waste beer yeast was studied. The main results were as follows:1. Using beer yeast powder as material, RNA was extracted form them by watery alkali method. The optimal extraction conditions were as following: Concentration of sodium hydroxide was 0.4% (w/v), extraction temperature was 100℃, extraction time was 1h, ration of alkali and yeast powder was 15mL: 1g, ration of ethanol and yeast powder was 10mL: 1g. Results showed that extraction rate of RNA was 5.25% and its content was 83.8%.2. Alkali combining with enzyme method was optimized as the best extraction method of extraction ofβ-(1,3)-D-glucan from beer yeast after comparing different extraction methods. The optimal extraction conditions were as following: Concentration of sodium hydroxide was 3% (w/v), extraction temperature was 80℃, extraction time was 2h, ration of alkali and yeast powder was 15mL: 1g, and dose of alkaline protease was 600 U/g. Results showed that extraction rate ofβ-(1,3)-D-glucan was 13.8% and its content was 85.2% and viscosity average molecular weight was 192KD. Extraction substances was only glucose determined using TLC method after hydrolyzation. Infrared Spectrum analysis showed that extraction substances wereβ-(1,3)-D-glucan with higher purity. 3. Protein was extracted from beer yeast using multiple steps method. The first step was pH value of upper clear liquid was adjusted by hydrochloric acid to 4.2~4.5 to deposit the protein after extraction of RNA. The second step was pH value of upper clear liquid was adjusted by hydrochloric acid to 3.8~4.1 to deposit the protein after extraction ofβ-(1,3)-D-glucan. Extraction rate of protein was 13.2% and its content was 79.1%, respectively. The content and composition of 8 kinds of limiting amino acids were coincident with the standard provided by FAO after analyzing amino acids in extracted protein.4. The factors influenced the determination ofβ-(1,3)-D-glucan confirmed by single factor and orthogonal design were in the order that concentration of pre-hydrolyzed sulfuric acid > hydrolyzing temperature > concentration of hydrolyzed sulfuric acid > hydrolyzing time. The optimum hydrolyzing conditions were as follows: pre-hydrolyzed sulfuric acid 12 mol/L, hydrolyzed sulfuric acid 2 mol/L, hydrolyzing temperature 100 oC and hydrolyzing time 24 h.5. Turgidity of the metatarsus and the quantity of antibody-generating cells of the mice after being orally fed with yeastβ-(1,3)-D-glucan for 30 days increased and yeast glucan had no effect on the phagocytosis index of monocyte macrophage. Results showed thatβ-(1,3)-D-glucan could strengthen the immunologic function of the cells and the body fluid of the mice, and had no effect on phagocytosis function of monocyte.