The feeding techniques in acarbose fermentation

Objective:To study the feeding techniques in acarbose fermentation.Methods:Maltose,or complex of maltose and yeast extract,was fed in various amounts at different times.Results:When maltose was fed once during the fermentation,the best effect was obtained by feeding maltose at 48 h.With the increase of the feed- ing amounts of maltose,the acarbose yield raised gradually.The highest acarbose yield of 3 462 mg·L~(-1),21% higher than control,was acquired at 48 h when 3% maltose was fed.When 1.2% maltose was fed three times at 36,48 and 60 h,acarbose yield reached 3 644 mg·L~(-1)at 96 h,27.4% higher than control.When the complex of maltose(total amount 3.6%)and yeast extract(total amount 0.125%)was fed three times at 36,48 and 60 h, acarbose yield reached 3 768 mg·L~(-1)at 108 h.However,further increasing of amount of yeast extract led to a in- crease in cell concentration and a decrease in acarbose yield obviously.Conclusion:When 3.0%～3.6% maltose was fed at 36～60 h,the acarbose yield increases obviously;additional feeding small amount of yeast extract is helpful for maintaining normal cell metabolism and increasing acarbose yield.However,when the feeding amount of yeast extract exceeds 0.25%,it stimulates the cell growth obviously and inhibits the biosynthesis of acarbose.