High-level production of heterologous proteins using untreated cane molasses and corn steep liquor in Escherichia coli medium

Appl Microbiol Biotechnol. 2010 Jun;87(2):517-25. doi: 10.1007/s00253-010-2536-0. Epub 2010 Mar 23.

Abstract

To develop an economical industrial medium, untreated cane molasses (UCM) was tested as a carbon source for fermentation culturing of Escherichia coli. To test the industrial application of this medium, we chose a strain co-expressing a carbonyl reductase (PsCR) and a glucose dehydrogenase (BmGDH). Although corn steep liquor (CSL) could be used as an inexpensive nitrogen source to replace peptone, yeast extract could not be replaced in E. coli media. In a volume of 40 ml per 1-l flask, a cell concentration of optical density (OD(600)) 15.1 and enzyme activities of 6.51 U/ml PsCR and 3.32 U/ml BmGDH were obtained in an optimized medium containing 25.66 g/l yeast extract, 3.88 g/l UCM, and 7.1% (v/v) CSL. When 3.88 g/l UCM was added to the medium at 6 h in a fed-batch process, the E. coli concentration increased to OD(600) of 24, and expression of both PsCR and BmGDH were twofold higher than that of a batch process. Recombinant cells from batch or fed-batch cultures were assayed for recombinant enzyme activity by testing the reduction of ethyl 4-chloro-3-oxobutanoate to ethyl (S)-4-chloro-3-hydroxybutanoate (CHBE). Compared to cells from batch cultures, fed-batch cultured cells showed higher recombinant enzyme expression, producing 560 mM CHBE in the organic phase with a molar yield of 92% and an optical purity of the (S)-isomer of >99% enantiomeric excess.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetoacetates / metabolism
  • Bioreactors / microbiology
  • Culture Media / analysis
  • Culture Media / metabolism*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Fermentation
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Gene Expression
  • Glucose 1-Dehydrogenase / genetics
  • Glucose 1-Dehydrogenase / metabolism*
  • Glucose Dehydrogenases / genetics
  • Glucose Dehydrogenases / metabolism*
  • Industrial Microbiology*
  • Molasses / analysis
  • Molasses / microbiology
  • Pichia / enzymology
  • Zea mays / metabolism
  • Zea mays / microbiology

Substances

  • Acetoacetates
  • Culture Media
  • Fungal Proteins
  • ethyl 4-chloro-3-oxobutanoate
  • Glucose Dehydrogenases
  • Glucose 1-Dehydrogenase