title: Decrease of 3-hydroxypropionaldehyde accumulation in 1,3-propanediol production by over-expressing dhaT gene in Klebsiella pneumoniae TUAC01.
abstract: Glycerol can be biologically converted to 1,3-propanediol, a key raw material required for the synthesis of polytrimethylene terephthalate and other polyester fibers. In 1,3-propanediol synthesis pathway, 3-hydroxypropionaldehyde (3-HPA) was an inhibitory intermediary metabolite. The accumulation of 3-HPA in broth would cause an irreversible cessation of the fermentation process. With the object of reducing 3-HPA level in the fermentation broth, dhaT gene which encodes 1,3-propanediol oxidoreductase (PDOR) was cloned and over expressed in 1,3-propanediol producing bacterium Klebsiella pneumoniae TUAC01. dhaT gene was linked downstream of the ptac promoter in an expressing vector pDK6 to form plasmid pDK-dhaT. The newly formed pDK-dhaT was transformed to K. pneumoniae TUAC01. Under the inducement of IPTG, PDOR was over-expressed when the constructed strain was cultured on an LB medium or a fermentation medium. A 5 L scale-up fermentation experiment was done to test the 3-HPA accumulation in broth, with the initial substrate glycerol 30 g/L; the peak levels of 3-HPA in broth were 7.55 and 1.49 mmol/L for control host strain and the constructed strain, respectively. In 50 g/L initial glycerol experiment, the peak level of 3-HPA in broth was 12.57 and 2.02 mmol/l for the control host strain and the constructed strain, respectively. Thus the fermentation cessation caused by the toxicity of 3-HPA was alleviated in the constructed strain.
authors: Department of Chemical Engineering, Tsinghua University, Beijing 100084, People's Republic of China. j-hao03@mails.tsinghua.edu.cn
authors: Jian
authors: J
authors: Hao
authors: Wei
authors: W
authors: Wang
authors: Jiesheng
authors: J
authors: Tian
authors: Jilun
authors: J
authors: Li
authors: Dehua
authors: D
authors: Liu
mesh_terms: D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000096:biosynthesis* / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis*; D019149:Bioreactors; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D018628:Gene Dosage; D015870:Gene Expression; D005786:Gene Expression Regulation; D005985:Glyceraldehyde / Q000031:analogs & derivatives* / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011407:Propane / Q000378:metabolism*; D011409:Propylene Glycols / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011409:Propylene Glycols; C047158:3-hydroxypropionaldehyde; D005985:Glyceraldehyde; D007544:Isopropyl Thiogalactoside; C041787:1,3-propanediol; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; C052370:1,3-propanediol dehydrogenase; D005990:Glycerol; D011407:Propane