Investigation of Malic Acid Production in Aspergillus oryzae under Nitrogen Starvation Conditions
Artikel i vetenskaplig tidskrift, 2013

Malic acid has great potential for replacing petrochemical building blocks in the future. For this application, high yields, rates, and titers are essential in order to sustain a viable biotechnological production process. Natural high-capacity malic acid producers like the malic acid producer Aspergillus flavus have so far been disqualified because of special growth requirements or the production of mycotoxins. As A. oryzae is a very close relative or even an ecotype of A. flavus, it is likely that its high malic acid production capabilities with a generally regarded as safe (GRAS) status may be combined with already existing large-scale fermentation experience. In order to verify the malic acid production potential, two wild-type strains, NRRL3485 and NRRL3488, were compared in shake flasks. As NRRL3488 showed a volumetric production rate twice as high as that of NRRL3485, this strain was selected for further investigation of the influence of two different nitrogen sources on malic acid secretion. The cultivation in lab-scale fermentors resulted in a higher final titer, 30.27 +/- 1.05 g liter(-1), using peptone than the one of 22.27 +/- 0.46 g liter(-1) obtained when ammonium was used. Through transcriptome analysis, a binding site similar to the one of the Saccharomyces cerevisiae yeast transcription factor Msn2/4 was identified in the upstream regions of glycolytic genes and the cytosolic malic acid production pathway from pyruvate via oxaloacetate to malate, which suggests that malic acid production is a stress response. Furthermore, the pyruvate carboxylase reaction was identified as a target for metabolic engineering, after it was confirmed to be transcriptionally regulated through the correlation of intracellular fluxes and transcriptional changes.

MICROARRAY

STRAIN

ACCUMULATION

METABOLISM

TOPOLOGY

PROTEIN

ESCHERICHIA-COLI

SACCHAROMYCES-CEREVISIAE

IDENTIFICATION

FLAVUS

Författare

Christoph Knuf

Chalmers, Kemi- och bioteknik, Livsvetenskaper, Systembiologi

Intawat Nookaew

Chalmers, Kemi- och bioteknik, Livsvetenskaper, Systembiologi

Stephen H. Brown

Novozymes Biotech, Inc.

Michael McCulloch

Novozymes Biotech, Inc.

Alan Berry

Novozymes Biotech, Inc.

Jens B Nielsen

Chalmers, Kemi- och bioteknik, Livsvetenskaper, Systembiologi

Applied and Environmental Microbiology

0099-2240 (ISSN) 1098-5336 (eISSN)

Vol. 79 19 6050-6058

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

Europeiska kommissionen (FP7), 2010-01-01 -- 2014-12-31.

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

Ämneskategorier

Mikrobiologi

DOI

10.1128/AEM.01445-13

Mer information

Skapat

2017-10-07