Conversion of orange peel to L-galactonic acid in a consolidated process using engineered strains of Aspergillus niger

Joosu Kuivanen (Corresponding Author), Hugo Dantas, Dominik Mojzita, E Mallmann, A Biz, N Krieger, D Mitchell, Peter Richard

Research output: Contribution to journalArticleScientificpeer-review

15 Citations (Scopus)


Citrus processing waste is a leftover from the citrus processing industry and is available in large amounts. Typically, this waste is dried to produce animal feed, but sometimes it is just dumped. Its main component is the peel, which consists mostly of pectin, with D-galacturonic acid as the main monomer. Aspergillus niger is a filamentous fungus that efficiently produces pectinases for the hydrolysis of pectin and uses the resulting D-galacturonic acid and most of the other components of citrus peel for growth. We used engineered A. niger strains that were not able to catabolise D-galacturonic acid, but instead converted it to L-galactonic acid. These strains also produced pectinases for the hydrolysis of pectin and were used for the conversion of pectin in orange peel to L-galactonic acid in a consolidated process. The D-galacturonic acid in the orange peel was converted to L-galactonic acid with a yield close to 90%. Submerged and solid-state fermentation processes were compared.
Original languageEnglish
Number of pages8
JournalAMB Express
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed



  • Aspergillus niger
  • citrus processing waste
  • consolidated bioprocessing
  • D-galacturonic acid
  • L-galactonic acid
  • orange peel

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