Physiological characterization of the high malic acid-producing Aspergillus oryzae strain 2103a-68
Journal article, 2014

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.

Metabolic engineering

Aspergillus oryzae

Dicarboxylic acid

PATHWAY

IDENTIFICATION

WIDE ANALYSIS

Xylose

RT-PCR

EXPRESSION

Malate

QUANTIFICATION

METABOLIC FLUX ANALYSIS

LOCALIZATION

ACCUMULATION

SACCHAROMYCES-CEREVISIAE

Author

Christoph Knuf

Chalmers, Chemical and Biological Engineering, Life Sciences, System Biology

Intawat Nookaew

Chalmers, Chemical and Biological Engineering, Life Sciences, System Biology

Ilse Remmers

Chalmers, Chemical and Biological Engineering, Life Sciences, System Biology

Sakda Khoomrung

Chalmers, Chemical and Biological Engineering, Life Sciences, System Biology

Stephen H. Brown

Novozymes Biotech, Inc.

Alan Berry

Novozymes Biotech, Inc.

Jens B Nielsen

Chalmers, Chemical and Biological Engineering, Life Sciences, System Biology

Applied Microbiology and Biotechnology

0175-7598 (ISSN) 1432-0614 (eISSN)

Vol. 98 8 3517-3527

Industrial Systems Biology of Yeast and A. oryzae (INSYSBIO)

European Commission (FP7), 2010-01-01 -- 2014-12-31.

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

Subject Categories

Microbiology

Areas of Advance

Life Science Engineering (2010-2018)

DOI

10.1007/s00253-013-5465-x

More information

Created

10/7/2017