Studes On Submerged Fermentation And Anti-tumor Activity Of Lachnum Sp.YM218Exopolysaccharide

Fungal extracellular polysaccharide is a type of polysaccharides that wassecreted outside the cells after synthesized in the intracellular of fungi. It was reportedthat extracellular polysaccharide from fungus had a high antitumor activity and hadhigh inhibition to the cancer cells. The extracellular polysaccharide would beachieved by submerged fermentation, due to its characteristics of high production andseparation from broth easily. In the present thesis, nutritional and non-nutritionalfactors, fermentation techniques, extraction techniques and antitumor activity ofextracellular polysaccharides from Lachnum sp.YM218were studied.In order to improve extracellular polysaccharides production from Lachnumsp.YM218, the compositions of medium were optimized by single factor test andorthogonal test successively, the results showed that the optimized medium wascomposed of glucose30g/L, yeast extract paste12.5g/L, Ca（OH）₂0.05g/L. Theoptimum culture conditions for YM218extracellular polysaccharides production wereas follows: the optimal pH, temperature and rotation speed were6.5,28℃and210r/min, respectively; Compared to original fermentation conditions, extracellularpolysaccharides production from YM218cultured under the above conditions wasincreased from4.247g/L to9.917g/L and increased by133.51%, while itsfermentation period was decreased to10days which was12days.Base on the shake culture experiments, submerged fermentation conditions of5liter auto-fermentor were studied. The results showed that optimum culture conditionswere material coefficient of0.5, agitation rate of230r/min, ventilatory of3L/min andinoculation quantity of10%. Under the above conditions, the yield of extracellularpolysaccharides was increased from11.756g/L to13.358g/L; compared to originalfermentation conditions it was raised13.63%.The extracting conditions of extracellular polysaccharides from Lachnumsp.YM218were determined as follows: pH of ferment liquid was changed to7.0,concentrated to1/4volume at55℃and then precipitated at a final75%ethanol at4℃overnight. The pellets were harvested by centrifuge, washed several times with100%ethanol, ether and acetone, and dried by vacuum refrigerator.The effects of YM218extracellular polysaccharides on inhibiting Hep-2cellstumor cells in vitro were studied. The results showed that YM218extracellularpolysaccharides extracted by50%alcohol precipitation had the best anti-tumor activity, and it inhibited proliferation of Hep-2cells in a concentration-dependentmanner, its IC₅₀value was0.13mg/mL.