Metabolic engineering of Escherichia coli W for isobutanol production on chemically defined medium and cheese whey as al
- PDF / 1,414,442 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 81 Downloads / 198 Views
BIOENERGY/BIOFUELS/BIOCHEMICALS - ORIGINAL PAPER
Metabolic engineering of Escherichia coli W for isobutanol production on chemically defined medium and cheese whey as alternative raw material Katharina Novak1 · Juliane Baar1 · Philipp Freitag1 · Stefan Pflügl1 Received: 3 September 2020 / Accepted: 3 October 2020 © The Author(s) 2020
Abstract The aim of this study was to establish isobutanol production on chemically defined medium in Escherichia coli. By individually expressing each gene of the pathway, we constructed a plasmid library for isobutanol production. Strain screening on chemically defined medium showed successful production in the robust E. coli W strain, and expression vector IB 4 was selected as the most promising construct due to its high isobutanol yields and efficient substrate uptake. The investigation of different aeration strategies in combination with strain improvement and the implementation of a pulsed fed-batch were key for the development of an efficient production process. E. coli W ΔldhA ΔadhE Δpta ΔfrdA enabled aerobic isobutanol production at 38% of the theoretical maximum. Use of cheese whey as raw material resulted in longer process stability, which allowed production of 20 g l−1 isobutanol. Demonstrating isobutanol production on both chemically defined medium and a residual waste stream, this study provides valuable information for further development of industrially relevant isobutanol production processes. Keywords Chemically defined medium · Promotor fine-tuning · Constitutive promotor · Pulsed fed-batch · Isobutanol adaptation
Introduction Second-generation biofuels, which are produced from lignocellulosic biomass or waste streams, are considered as strategically important sustainable fuels due to their renewability, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10295-020-02319-y) contains supplementary material, which is available to authorized users. * Stefan Pflügl [email protected] Katharina Novak [email protected] Juliane Baar [email protected] Philipp Freitag philipp.Freitag@freitag‑edv.at 1
Institute for Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
biodegradability and low emissions of greenhouse gases [1]. The production of higher molecular weight alcohols such as n-butanol and isobutanol poses advantages over ethanol production. Both alcohols have a higher energy content closer to gasoline, can be transported using existing infrastructure and their lower vapor pressures improves mixing with gasoline [2, 3]. Isobutanol has a higher octane number than n-butanol, is less toxic to cells and requires less energy for downstream processing [2]. Biotechnologically, the isobutanol pathway is less complex and not acetyl-CoA dependent, which results in lower side-product formation compared to n-butanol production [4]. Isobutanol is a metabolite not naturally synthesized by any or
Data Loading...
