Controlling substrate concentration in fed-batch candida magnoliae culture increases mannitol production.
Candida magnoliae HH-01, a yeast strain that is currently used for the industrial production of mannitol, has the highest mannitol production ever reported for a mannitol-producing microorganism. However, when the fructose concentration exceeds 150 g/L, the volumetric mannitol production rate decreases because of a lag in mannitol production, and the yield decreases as a result of the formation of side products. In fed-batch culture, the volumetric production rate and mannitol yield from fructose vary substantially with the fructose concentration and are maximal at a controlled fructose concentration of 50 g/L. In continuous feeding experiments, the maximum mannitol yield was 85% (g/g) at a glucose/fructose feeding ratio of 1/20. A high glucose concentration in the production phase resulted in the formation of ethanol followed by a decrease in yield and productivity. NAD(P)H-dependent mannitol dehydrogenase was purified to homogeneity from C. magnoliae. In vitro, mannitol dehydrogenase was inhibited by increasing ethanol concentration. Mannitol product was also found to be inhibitory with a K(i) of 183 mM. Under optimum conditions, a final mannitol production of 213 g/L was obtained from 250 g fructose/L after 110 h.
Lee
Jung-Kul
JK
BioNgene Co., Ltd., 10-1, 1Ka, Myungryun-Dong, Jongro-Ku, Seoul, 110-521, Korea. jkrhee@biongene.com
Song
Ji-Yoon
JY
Kim
Sang-Yong
SY
D019149:Bioreactors / Q000382:microbiology*; D002175:Candida / Q000145:classification / Q000254:growth & development* / Q000378:metabolism*; D018929:Cell Culture Techniques / Q000379:methods*; D005246:Feedback; D005632:Fructose / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods; D008353:Mannitol / Q000378:metabolism*; D008354:Mannitol Dehydrogenases / Q000378:metabolism*; D011786:Quality Control; D013379:Substrate Specificity; D013696:Temperature
D005632:Fructose; D008353:Mannitol; D008354:Mannitol Dehydrogenases; D005947:Glucose