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Physiological characterization of the high malic acid-producing Aspergillus oryzae strain 2103a-68

Christoph Knuf (Institutionen för kemi- och bioteknik, Systembiologi) ; Intawat Nookaew (Institutionen för kemi- och bioteknik, Systembiologi) ; Ilse Remmers (Institutionen för kemi- och bioteknik, Systembiologi) ; Sakda Khoomrung (Institutionen för kemi- och bioteknik, Systembiologi) ; S. Brown ; A. Berry ; Jens B. Nielsen (Institutionen för kemi- och bioteknik, Systembiologi)
Applied Microbiology and Biotechnology (0175-7598). Vol. 98 (2014), 8, p. 3517-3527.
[Artikel, refereegranskad vetenskaplig]

Malic acid is a C-4 dicarboxylic acid that is currently mainly used in the food and beverages industry as an acidulant. Because of the versatility of the group of C-4 dicarboxylic acids, the chemical industry has a growing interest in this chemical compound. As malic acid will be considered as a bulk chemical, microbial production requires organisms that sustain high rates, yields, and titers. Aspergillus oryzae is mainly known as an industrial enzyme producer, but it was also shown that it has a very competitive natural production capacity for malic acid. Recently, an engineered A. oryzae strain, 2103a-68, was presented which overexpressed pyruvate carboxylase, malate dehydrogenase, and a malic acid transporter. In this work, we report a detailed characterization of this strain including detailed rates and yields under malic acid production conditions. Furthermore, transcript levels of the genes of interest and corresponding enzyme activities were measured. On glucose as carbon source, 2103a-68 was able to secrete malic acid at a maximum specific production rate during stationary phase of 1.87 mmol (g dry weight (DW))(-1) h(-1) and with a yield of 1.49 mol mol(-1). Intracellular fluxes were obtained using C-13 flux analysis during exponential growth, supporting the success of the metabolic engineering strategy of increasing flux through the reductive cytosolic tricarboxylic acid (rTCA) branch. Additional cultivations using xylose and a glucose/xylose mixture demonstrated that A. oryzae is able to efficiently metabolize pentoses and hexoses to produce malic acid at high titers, rates, and yields.

Nyckelord: Malate, Dicarboxylic acid, Aspergillus oryzae, Metabolic engineering, Xylose, METABOLIC FLUX ANALYSIS, SACCHAROMYCES-CEREVISIAE, WIDE ANALYSIS, RT-PCR, QUANTIFICATION, PATHWAY, IDENTIFICATION, LOCALIZATION, ACCUMULATION, EXPRESSION



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Denna post skapades 2014-05-27. Senast ändrad 2017-01-17.
CPL Pubid: 198611

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Systembiologi (2008-2014)

Ämnesområden

Livsvetenskaper
Mikrobiologi

Chalmers infrastruktur

C3SE/SNIC (Chalmers Centre for Computational Science and Engineering)

 


Projekt

Denna publikation är ett resultat av följande projekt:


Industrial Systems Biology of Yeast and A. oryzae (INSYSBIO) (EC/FP7/247013)