title: Effects and mechanisms of H(2)O(2) on production of dicarboxylic acid.
abstract: The system of producing long chain dicarboxylic acid (DCA) by Candida tropicalis is an aerobic and viscous fermentation system. A method to overcome the gas-liquid transport resistance and to increase oxygen supply is by adding hydrogen peroxide (H(2)O(2)) to the fermentation system. Here we report that the H(2)O(2) not only can enhance the oxygen supply but also change the metabolism by inducing cytochrome P450, the key enzyme of a, o-oxidation. When C. tropicalis was cultivated in a 3-L bioreactor using the combination of aeration and H(2)O(2) feeding, DCA production rates increased by about 10% after a short period of decrease at the beginning. Furthermore, the experiments showed that the maximum activities of P450 could be induced at 2 mM H(2)O(2), and the inducible mechanisms are also discussed. Moreover, we suggest that alkane might be oxidized through the "peroxide shunt pathway" when H(2)O(2) is present. By adding H(2)O(2), the DCA yield in a 22-L bioreactor could increase by 25.3% and reach 153.9 g/L.
authors.affiliation: Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, P.R. China, 100084. jiaopeng@tsinghua.edu.cn
authors.forename: P
authors.initials: P
authors.lastname: Jiao
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Hua
authors.forename: Z
authors.initials: Z
authors.lastname: Cao
mesh_terms: D000332:Aerobiosis; D019149:Bioreactors; D002175:Candida / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects* / Q000378:metabolism; D003998:Dicarboxylic Acids / Q000138:chemical synthesis*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008962:Models, Theoretical; D010100:Oxygen / Q000378:metabolism*; D010865:Pilot Projects
chemical_list: D003998:Dicarboxylic Acids; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; D010100:Oxygen