Applied Genetics and Molecular Biotechnology

Applied Microbiology and Biotechnology

, Volume 87, Issue 3, pp 1045-1055

Open Access This content is freely available online to anyone, anywhere at any time.

Engineering Corynebacterium glutamicum for isobutanol production

  • Kevin Michael SmithAffiliated withDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles
  • , Kwang-Myung ChoAffiliated withDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles
  • , James C. LiaoAffiliated withDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles Email author 

Abstract

The production of isobutanol in microorganisms has recently been achieved by harnessing the highly active 2-keto acid pathways. Since these 2-keto acids are precursors of amino acids, we aimed to construct an isobutanol production platform in Corynebacterium glutamicum, a well-known amino-acid-producing microorganism. Analysis of this host’s sensitivity to isobutanol toxicity revealed that C. glutamicum shows an increased tolerance to isobutanol relative to Escherichia coli. Overexpression of alsS of Bacillus subtilis, ilvC and ilvD of C. glutamicum, kivd of Lactococcus lactis, and a native alcohol dehydrogenase, adhA, led to the production of 2.6 g/L isobutanol and 0.4 g/L 3-methyl-1-butanol in 48 h. In addition, other higher chain alcohols such as 1-propanol, 2-methyl-1-butanol, 1-butanol, and 2-phenylethanol were also detected as byproducts. Using longer-term batch cultures, isobutanol titers reached 4.0 g/L after 96 h with wild-type C. glutamicum as a host. Upon the inactivation of several genes to direct more carbon through the isobutanol pathway, we increased production by ∼25% to 4.9 g/L isobutanol in a ∆pycldh background. These results show promise in engineering C. glutamicum for higher chain alcohol production using the 2-keto acid pathways.

Keywords

Biofuel Isobutanol C. glutamicum