Selection of mutants of Aspergillus niger showing enhanced productivity of citric acid from starch in shaking culture

Sugima Rugsaseel, Kohtaro Kirimura, Shoji Usami

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Mutants with enhanced citric acid production from soluble starch were induced from Aspergillus niger WU-2223L. After UV-irradiation of a conidial suspension of strain WU-2223L, mutants were selected on modified starch-methyl red agar plates on the basis of higher amylolytic activity and acid productivity. The 8 mutants selected showed enhanced citric acid production from soluble starch in shaking culture. Among them, a representative mutant strain, 2M-43, produced 48.0gg/l of citric acid from 120 g/l of soluble starch in 9 d of cultivation in shaking culture, whereas strain WU-2223L produced 35.1 g/l. Glucoamylase activities in the culture filtrates of strains 2M-43 and WU-2223L reached maximum levels of 3.62 U/ml and 2.11 U/ml, respectively, both at 3 d of cultivation, and thereafter decreased.

Original languageEnglish
Pages (from-to)226-228
Number of pages3
JournalJournal of Fermentation and Bioengineering
Issue number3
Publication statusPublished - 1993


ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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