title: 3-Hydroxypropionaldehyde guided glycerol feeding strategy in aerobic 1,3-propanediol production by Klebsiella pneumoniae.
abstract: 3-Hydroxypropionaldehyde (3-HPA) is a toxic intermediary metabolite in the biological route of 1,3-propanediol biosynthesis from glycerol. 3-HPA accumulated in culture medium would arouse an irreversible cessation of the fermentation process. The role of substrate (glycerol) on 3-HPA accumulation in aerobic fermentation was investigated in this paper. 1,3-Propanediol oxidoreductase and glycerol dehydratase, two key enzyme catalyzing reactions of 3-HPA formation and consumption, were sensitive to high concentration of 3-HPA. When the concentration of 3-HPA increased to a higher level in medium (ac 10 mmol/L), the activity of 1,3-propanediol oxidoreductase in cell decreased correspondingly, which led to decrease of the 3-HPA conversion rate, then the 3-HPA concentration increasing was accelerated furthermore. 3-HPA accumulation in culture medium was triggered by this positive feedback mechanism. In the cell exponential growth phase, the reaction catalyzed by 1,3-propanediol oxidoreductase was the rate limiting step in 1,3-propanediol production. The level of 3-HPA in culture medium could be controlled by the substrate (glycerol) concentration, and lower level of glycerol could avoid 3-HPA accumulating to a high, lethal concentration. In fed batch fermentation, under the condition of initial glycerol concentration 30 g/L, and keeping glycerol concentration lower than 7-8 g/L in cell exponential growth phase, 3-HPA accumulation could not be incurred. Based on this result, a glycerol feeding strategy was set up in fed batch fermentation. Under the optimized condition, 50.1 g/L of 1,3-propanediol was produced in 24 h, and 73.1 g/L of final 1,3-propanediol concentration was obtained in 54 h.
authors.affiliation: Department of Chemical Engineering, Tsinghua University, 100084, Beijing, People's Republic of China, j-hao03@mails.tsinghua.edu.cn
authors.forename: Jian
authors.initials: J
authors.lastname: Hao
authors.forename: Rihui
authors.initials: R
authors.lastname: Lin
authors.forename: Zongming
authors.initials: Z
authors.lastname: Zheng
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Dehua
authors.initials: D
authors.lastname: Liu
mesh_terms: D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D003470:Culture Media; D005285:Fermentation; D005985:Glyceraldehyde / Q000031:analogs & derivatives* / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism*; D006836:Hydro-Lyases / Q000378:metabolism; D007218:Industrial Microbiology; D007711:Klebsiella pneumoniae / Q000378:metabolism*; D011407:Propane / Q000378:metabolism*; D011409:Propylene Glycols / Q000378:metabolism*
chemical_list: D003470:Culture Media; D011409:Propylene Glycols; C047158:3-hydroxypropionaldehyde; D005985:Glyceraldehyde; C041787:1,3-propanediol; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; C052370:1,3-propanediol dehydrogenase; D006836:Hydro-Lyases; C020671:glycerol dehydratase; D005990:Glycerol; D011407:Propane