l-Isoleucine Production with Corynebacterium glutamicum: Further Flux Increase and Limitation of Export.

Applied and Environmental Microbiology
S MorbachL Eggeling

Abstract

The synthesis of l-isoleucine with Corynebacterium glutamicum involves 11 reaction steps, in at least five of which activity or expression is regulated. We used four genes and alleles encoding feedback-resistant enzymes (Fbr) in various combinations to assay flux increase through the sequence. During strain construction, the order of genes overexpressed was important. Only when ilvA(Fbr) was first overexpressed could hom(Fbr) be introduced. This succession apparently prevents the toxic accumulation of biosynthesis intermediates. The best strain constructed (SM13) was characterized by high-level expression of hom(Fbr), thrB, and ilvA(Fbr). With this strain a yield of 0.22 g of l-isoleucine per g of glucose was obtained, with a maximal specific productivity of 0.10 g of l-isoleucine per g (dry weight) per h. In strain SM13, with the high metabolite flux through the reaction sequence, effects on (i) other enzyme levels, (ii) time-dependent variations with process time, and (iii) concentrations of cytosolic intermediates were quantified. Most importantly, the intracellular l-isoleucine concentration is always higher at all process times than the extracellular concentration. The intracellular concentration rises to 110 mM, whereas e...Continue Reading

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Citations

Jun 3, 2010·Biotechnology Journal·Jin Hwan Park, Sang Yup Lee
Feb 18, 2011·Bioengineered Bugs·Jose-Luis Adrio, Arnold L Demain
Oct 11, 2014·Applied Microbiology and Biotechnology·Michael VogtLothar Eggeling
May 30, 2015·BMC Microbiology·Ulrike Sorger-HerrmannVolker F Wendisch
Jan 22, 2019·Applied Microbiology and Biotechnology·Xiaoyuan Wang
Sep 3, 2013·Applied and Environmental Microbiology·Kristina HoffmannLothar Eggeling
Oct 22, 2008·Applied and Environmental Microbiology·Jan Marienhagen, Lothar Eggeling
Sep 2, 2008·Applied Microbiology and Biotechnology·Anthony F Cann, James C Liao
Jun 27, 2012·Journal of Industrial Microbiology & Biotechnology·Xixian XieNing Chen
May 23, 2013·Applied Microbiology and Biotechnology·Pengfei GuQingsheng Qi
Oct 28, 2009·Applied Microbiology and Biotechnology·Anthony F Cann, James C Liao
Apr 19, 2015·Microbial Cell Factories·Mireille GinesyUlrika Rova
Oct 22, 2009·Applied Microbiology and Biotechnology·Jin Hwan Park, Sang Yup Lee
Oct 13, 2018·Biotechnology and Applied Biochemistry·Wenjian MaXiaoyuan Wang

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