Studies On Technology Of Pleurotus Ostreatus Submerged Fermentation And Its Polysaccharide Extraction And Purification

Process of Pleurotus ostreatus submerged fermentation and its polysaccharideextraction and purification were studied in this paper. The optimum conditions ofPleurotus ostreatus submerged fermentation and its polysaccharide extraction andpurification were determined. The main results were as follows:1. Five Pleurotus ostreatus strains were compared by flask cultivation and Suyin-6was determined as tested strain.2. By monofactorial and orthogonal test, an optimum medium had been determined.The medium composition was as follow: 6% glucose, 0.3% (NH₄)₂SO₄, 0.5% corn steepliquor, 0.1% KH₂PO₄, 0.1% MgSO₄. The production of 28.82g/L biomass and 5.43g/Lextracellular polysaccharide were obtained on this medium by flask cultivation.3. The result of Time-course in shaking flask culture showed that pH of fermentingliquid dropped at first, then went up and dropped again at last on condition that pH wasn'tbe controlled. The production of extracellular polysaccharide reached maximum amountwhen pH had dropped second time. So the change of pH could be looked on as one of theimportant targets which fermention was ended up. The result of fermentation experimentin 10L fermentor showed that the production of 16.67g/L biomass and 5.22g/Lextracellular polysaccharide were obtained when the fermentative time was 5 days.4. By orthogonal test, the extractive conditions of mycelial polysaccharide weredetermined as follows: water / mycelia = 4/1, extracting temperature 55℃, extractingtime 6h, extracting solution / ethanol=1/3.5. Crude polysaccharides were preliminary purified by deproteinization with Sevag'sreagents combined with protease digestion, deionization with dialysis and concentration.6. The preliminary purified polysaccharides were further graded and purified byDEAE cellulose coIume. As a result, three factions in EPS were obtained. They werenamed as EPS-â… , EPS-II and EPS-â…¢. EPS-â…¡was the main and large faction. Threefactions in MPS were obtained too. They were named as MPS-â… , MPS-â…¡and MPS-â…¢.MPS-â… and MPS-â…¡were the main factions.7. EPS-â…¡, MPS-â… and MPS-â…¡were further graded and purified by Sephadex G-200column chromatography. The result showed that the molecular weight of the two factionswere similar which obtained in EPS-â…¡, MPS-â… and MPS-â…¡, respectively. EPS-â…¡-1represented 63% total amount. MPS-â… -2 represented 90% of total amount. MPS-â…¡-2represented 94% of total amount.