title: Microbial conversion of glycerol to 1,3-propanediol by an engineered strain of Escherichia coli.
abstract: In an effort to improve industrial production of 1,3-propanediol (1,3-PD), we engineered a novel polycistronic operon under the control of the temperature-sensitive lambda phage P(L)P(R) promoter regulated by the cIts857 repressor and expressed it in Escherichia coli K-12 ER2925. The genes for the production of 1,3-PD in Clostridium butyricum, dhaB1 and dhaB2, which encode the vitamin B(12)-independent glycerol dehydratase DhaB1 and its activating factor, DhaB2, respectively, were tandemly arrayed with the E. coli yqhD gene, which encodes the 1,3-propanediol oxidoreductase isoenzyme YqhD, an NADP-dependent dehydrogenase that can directly convert glycerol to 1,3-PD. The microbial conversion of 1,3-PD from glycerol by this recombinant E. coli strain was studied in a two-stage fermentation process. During the first stage, a novel high-cell-density fermentation step, there was significant cell growth and the majority of the metabolites produced were organic acids, mainly acetate. During the second stage, glycerol from the fresh medium was rapidly converted to 1,3-PD following a temperature shift from 30 degrees C to 42 degrees C. The by-products were mainly pyruvate and acetate. During this two-stage process, the overall 1,3-PD yield and productivity reached 104.4 g/liter and 2.61 g/liter/h, respectively, and the conversion rate of glycerol to 1,3-PD reached 90.2% (g/g). To our knowledge, this is the highest reported yield and productivity efficiency of 1,3-PD with glycerol as the sole source of carbon. Furthermore, the overall fermentation time was only 40 h, shorter than that of any other reports.
authors.affiliation: Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, 2901 Beidi Rd., Shanghai 201106, People's Republic of China. xueming70@gmail.com
authors.forename: Xueming
authors.initials: X
authors.lastname: Tang
authors.forename: Yongsong
authors.initials: Y
authors.lastname: Tan
authors.forename: Hong
authors.initials: H
authors.lastname: Zhu
authors.forename: Kai
authors.initials: K
authors.lastname: Zhao
authors.forename: Wei
authors.initials: W
authors.lastname: Shen
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010582:Bacteriophage lambda / Q000235:genetics; D001711:Biotransformation; D046972:Clostridium butyricum / Q000235:genetics; D048168:Escherichia coli K12 / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism*; D006836:Hydro-Lyases / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011409:Propylene Glycols / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism; D011995:Recombination, Genetic; D013696:Temperature
chemical_list: D011409:Propylene Glycols; C041787:1,3-propanediol; D019289:Pyruvic Acid; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; C052370:1,3-propanediol dehydrogenase; D006836:Hydro-Lyases; C020671:glycerol dehydratase; D005990:Glycerol; D019342:Acetic Acid