Separation And Purification Of Glutathione And S-Adenosyl-L-Methionine From Saccharomyces Cerevisiae

Glutathione (GSH) and S-adenosyl-L-methionine (SAM) are both physiological active compound with important functions, and present in almost all living organisms. They are both widely used in clinical medicine and food processing. Microorganism fermentation is the main method of production of GSH and SAM, and yeast is the most commonly used production strain. GSH and SAM are both the intracellular metabolites of the yeast and the fungal polysaccharides and polysaccharide-protein complexes both belong to cell wall as the extracellular. The compounds all have high economic value.This study investigated optimization and scale-up of separation and purification of GSH and SAM produced by fermentation, isolation method of β-glucan from spent yeast, process route of the comprehensive utilization of yeast. Specific contents are shown as follows:(1) Synthetic media was used in fermentative production of GSH instead of natural media and the yield of GSH reached 2g/L. The separation process route was established, including microwave extraction, ultrafiltration, concentration, ion-exchange chromatography, nanofiltration, macroporous adsorption chromatography and crystallization. The optimization of ion-exchange chromatography is as follows:flow velocity 1BV/h, wash water volume 8BV,0.05mol/L and 0.15mol/L HCl used as eluent. The pilot scale experiment was operated on the basis of the lab scale experiment, total yield reached 40% and purity of GSH above 95%. The separation cost is 738 RMB per kilogram GSH.(2) The separation process route of SAM was established, including extraction using hot water, ultrafiltration, ion-exchange chromatography, decoloring, nanofiltration and arefaction. Series of chromatographic columns were used in ion-exchange chromatography and optimal conditions were concentration of loading solution lOg/L, flow velocity 2BV/h, wash water volume 4BV, two columns in series as the elution mode. The resin adsorption capacity reached more than 210g/L, which was three times as much as the single column. The total yield of separation process on the lab scale was 65.5% and the purity of SAM was over 96%. The large scale experiment was carried out in Tibet Jinke Group Company, the total yield was 50% and the purity of SAM was over 96%. The separation cost was 337 RMB per kilogram SAM.(3) Co-separation strategy of SAM and GSH was established, the yield of SAM and GSH was 65% and 40% respectively and the purity of SAM and GSH was 96% and 95% respectively. The co-separation cost was 345 RMB per 1 kilogram SAM and 0.1 kilogram GSH, saving 16% of separation cost and all the fermentation cost of GSH. In addition, β-glucan was isolated from spent yeast using alkaline method, alkaline-acid method and enzyme-alkaline method. The enzyme-alkaline had the best extraction result that the yield was over 80% and the purity of β-glucan was more than 90%. The comprehensive utilization of yeast was designed to extract SAM, GSH and P-glucan in order to make full use of the yeast cells.