Contribution of cyanide-insensitive respiratory pathway, catalyzed by the alternative oxidase, to citric acid production in aspergillu

Kohtaro Kirimura, Masashi Yoda, Hideki Shimizu, Shuji Sugano, Makoto Mizuno, Kuniki Kino, Shoji Usami

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Abstract

In Aspergillus niger, a cyanide (CN)- and antimycin A-insensitive and salicylhydroxamic acid (SHAM)-sensitive respiratory pathway exists besides the cytochrome pathway and is catalyzed by the alternative oxidase (AOX). In this study, A. niger WU-2223L, a citric acid-producing strain, was cultivated in a medium containing 120 g/l of glucose, which is the concentration usually needed for citric acid production, and the effects of 2% (v/v) methanol, an inducer of citric acid, 2 μM antimycin A, and 1 mM SHAM on AOX activities and citric acid production were investigated. The AOX activity, measured as duroquinol oxidase, was localized in the purified mitochondria regardless of the presence of any additives. When WU-2223L was cultivated with antimycin A or methanol, both citric acid production and citric acid productivity, shown as the ratio of production per mycelial dry weight, increased with the increase of both the activity of AOX and the rate of CN-insensitive and SHAM-sensitive respiration. On the other hand, when WU-2223L was cultivated with SHAM, an inhibitor of AOX, the CN-insensitive and SHAM-sensitive respiration was not detected and the citric acid production and the productivity drastically decreased, although mycelial growth was not affected. These results clearly indicated that the CN-insensitive and SHAM-sensitive respiration catalyzed by AOX, localized in the mitochondria, contributed to citric acid production by A. niger.

Original languageEnglish
Pages (from-to)2034-2039
Number of pages6
JournalBioscience, Biotechnology and Biochemistry
Volume64
Issue number10
DOIs
Publication statusPublished - 2000 Jan 1

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Keywords

  • Alternative oxidase
  • Aspergillus niger
  • Citric acid
  • Cyanide-insensitive respiration
  • Mitochondria

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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