1. Inactivation of dhaD and dhaK abolishes by-product accumulation during 1,3-propanediol production in Klebsiella pneumoniae
- Author
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Chih-Ching Chien, Yu-Hong Wei, Kai-Chih Chang, Yu-Tze Horng, Po-Chi Soo, Chung-Jen Yu, and Ta-Chung Chou
- Subjects
Arabinose ,Ethanol ,Glycerol dehydratase ,Bioengineering ,Dehydrogenase ,PBAD promoter ,Biology ,Applied Microbiology and Biotechnology ,chemistry.chemical_compound ,Klebsiella pneumoniae ,Phosphotransferases (Alcohol Group Acceptor) ,chemistry ,Biochemistry ,Bacterial Proteins ,Product inhibition ,Propylene Glycols ,Fermentation ,Glycerol dehydrogenase ,1,3-Propanediol ,Gene Silencing ,Lactic Acid ,Butylene Glycols ,Biotechnology ,Sugar Alcohol Dehydrogenases - Abstract
1,3-Propanediol (1,3-PD) can be used for the industrial synthesis of a variety of compounds, including polyesters, polyethers, and polyurethanes. 1,3-PD is generated from petrochemical and microbial sources. 1,3-Propanediol is a typical product of glycerol fermentation, while acetate, lactate, 2,3-butanediol, and ethanol also accumulate during the process. Substrate and product inhibition limit the final concentration of 1,3-propanediol in the fermentation broth. It is impossible to increase the yield of 1,3-propanediol by using the traditional whole-cell fermentation process. In this study, dhaD and dhaK, the genes for glycerol dehydrogenase and dihydroxyacetone kinase, respectively, were inactivated by homologous recombination in Klebsiella pneumoniae. The dhaD/dhaK double mutant (designated TC100), selected from 5,000 single or double cross homologous recombination mutants, was confirmed as a double cross by using polymerase chain reaction. Analysis of the cell-free supernatant with high-performance liquid chromatography revealed elimination of lactate and 2,3-butanediol, as well as ethanol accumulation in TC100, compared with the wild-type strain. Furthermore, 1,3-propanediol productivity was increased in the TC100 strain expressing glycerol dehydratase and 1,3-PDO dehydrogenase regulated by the arabinose P(BAD) promoter. The genetic engineering and medium formulation approaches used here should aid in the separation of 1,3-propanediol from lactate, 2,3-butanediol, and ethanol and lead to increased production of 1,3-propanediol in Klebsiella pneumoniae.
- Published
- 2009