Metabolic Engineering of Fungal Strains for Conversion of D-Galacturonate to meso-Galactarate

Dominik Mojzita, Marilyn Wiebe, Satu Hilditch, Harry Boer, Merja Penttila, Peter Richard*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

D-Galacturonic acid can be obtained by hydrolyzing pectin, which is an abundant and low value raw material. By means of metabolic engineering, we constructed fungal strains for the conversion of D-galacturonate to meso-galactarate (mucate). Galactarate has applications in food, cosmetics, and pharmaceuticals and as a platform chemical. In fungi D-galacturonate is catabolized through a reductive pathway with a D-galacturonate reductase as the first enzyme. Deleting the corresponding gene in the fungi Hypocrea jecorina and Aspergillus niger resulted in strains unable to grow on D-galacturonate. The genes of the pathway for D-galacturonate catabolism were upregulated in the presence of D-galacturonate in A. niger, even when the gene for D-galacturonate reductase was deleted, indicating that D-galacturonate itself is an inducer for the pathway. A bacterial gene coding for a D-galacturonate dehydrogenase catalyzing the NAD-dependent oxidation of D-galacturonate to galactarate was introduced to both strains with disrupted D-galacturonate catabolism. Both strains converted D-galacturonate to galactarate. The resulting H. jecorina strain produced galactarate at high yield. The A. niger strain regained the ability to grow on D-galacturonate when the D-galacturonate dehydrogenase was introduced, suggesting that it has a pathway for galactarate catabolism.

Original languageEnglish
Pages (from-to)169-175
Number of pages7
JournalApplied and Environmental Microbiology
Volume76
Issue number1
DOIs
Publication statusPublished - Jan 2010
MoE publication typeA1 Journal article-refereed

Keywords

  • MOLD HYPOCREA-JECORINA
  • PSEUDOMONAS-SYRINGAE
  • ACID DEHYDROGENASE
  • IDENTIFICATION
  • PURIFICATION
  • CATABOLISM
  • PATHWAY

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