Studies On Fermentative Process Of Gellan Gum Using Starch Hydrolyzate

Gellan gum is one of the industrially useful exopolysaccharides which has widely used in food,pharmaceutical,chemical and other industries.A yellow-pigment strain Sphingomonas paucimobilis WZW002 and A yellow-pigment-free strain Sphingomonas paucimobilis WZ013 are used as research materials in this paper.In order to reduce the cost of production,the fermentative process of gellan gum using starch is investigated.And the rapid determination of gellan gum is investigated to monitor the fermentative process and determinate the quality of its products.The m-hydroxybiphenyl determinating gellan gum is investigated.The industrial high acyl and low acyl gellan gum have good linearity with its absorbance in the range of 0?0.20 mg/mL in the optimum reaction conditions,and the interference of glucose is also studied.When the concentration of glucose is not more than that of gellan gum,the interference is not half apparently.So the method is suitable to rapidly determination of pure gellan gum and gellan gum in the end of fermentatiom.The hydrolysis process of starch acting as cheap substitute of sucrose or glucose in gellan gum production is studied.And determine the relevant parameters of liquefication and saccharication crafts:the concentration 200 g/L,quantity of thermostable alpha-amylase 6x102 U/g starch,liquefied time 40 minutes,liquefied end point dextrose equivalent value may controls between 15%?20%,glucoamylase 60×102 U/g starch,and then the curve about hydrolysis time and dextrose equivalent is established.When the hydrolysis time is 6th hour,the dextrose equivalent reaches 100%.The fermentative process of gellan gum using starch and two strains above is investigated.When the concentration of corn starch is 40 g/L and dextrose equivalent is 80%,the cost is cheaper and the yield of gellan gum is highest by comparing different carbon source in the shake flasks.And later the 5 L bacth fermentation is conducted,the cycle of fermentation is 64 hours,and the yield of Sphingomonas sp.WZW002 reaches 12.5 g/L,viscosity 17100 mpa·s,and Sphingomonas sp.WZ013 9.43 g/L,viscosity 10940 mpa s.And then the Sphingomonas sp.WZW002 and starch hydrolyzate are used in the 5 L fed-batch fermentation.When the cultre is supplemented with 10 g/L corn starch hydrolyzate and its dextrose equivalent 80%at 24th hour,the yield reaches 17.5 g/L,viscosity 20140 mpa·s is determined.Ultimately the yield of gellan gum is increased by 31.6%compared with the batch fermentation.