Studies On Streptococcus Zooepidemicus Fermentation For Hyaluronic Acid

hyaluronic acid（HA）is a high molecular weight linear polysaccharide made upwith N-acetyl glucosamine and glucuronic acid which are connected repeatedly by β-1-3and β-1-4glycoside bonds.Due to its special physiological action,HA is widelyapplied to areas including medical,cosmetic and foodstuff industry. There are mainlytwo ways to obtain the hyaluronic acid: tissues extraction and fermentation bymicrobial. Because of shortage of material source, high cost, Limited production, theprice of HA is so extremely expensive.But the ways of fermentation by microbialcould to overcome the above disadvantages and has a boadly prospect.In this study, the origingal strain was Streptococcus zooepidemicusSL-1.it wasmutated by ultraviolet radiation and NTG.A high HA-production strain SL-2wasacquired which can produce HA55.17%higher than that of original strain. The flaskshaking inoculums culture conditions of SL-2were discussed,The results showed:glucose was suitable carbon source;the best nitrogen source was dusty yeast andpeptone;the rotate speed was150r/min and the temperature was37℃.The flaskshaking fermentation medium composition of SL-2was optimized using ortheogonalexperim ental design,the optimized culture medium was composed of glucose40g/L,beef extract4g/L,yeast7g/L, peptone9g/L, MgSO₄·7H₂O₂.5g/L, KH₂PO₄2.2g/L, the temperature35℃,100mL medium in500mL flask.finally the yield ofhyaluronic acid was0.5066g/L.The kinetic model was proposed based on the Monod and Luedeking Piretequations of cell growth, product formation and substrate consumption which couldprovided reasonable description for the fermentation process under various initialsugar conditions.through the analysis for model and parameters.we could understoodthat the hysluronic acid fermentation exists a suitibale range of initial sugar whichwas30g/L-60g/L.With experimental data in5L bioreactor always proved Thecalculated results of models was right.Consider the effects of HAfenmentation wasinterfered by LA,fermentation period, transformation ratio and conversion rate.wechoosed the initial suger concentration45g/L was the starting point of the nextreseach to optimize the culture conditions of Streptococcus zooepidemicusSL-2.Theoptimum pH value for HA accumulation was6.9, optimum temperature was34℃,optimum throughput was1.5L/min, optimum and optimum stir speed we for HA accumulation was600r/min. In this conditions, transformation ratio of HA was9.68%and the conversion rate was0.197g/（L h）.