Journal of Industrial Microbiology

, Volume 5, Issue 4, pp 229–237 | Cite as

Mutation and screening to increase chymosin yield in a genetically-engineered strain ofAspergillus awamori

  • Michael Lamsa
  • Peggy Bloebaum
Original Papers


Through the course of five rounds of mutagenesis of a genetically-engineered strain ofAspergillus awamori, the yield of a heterologous protein (the acid protease, calf chymosin) increased four-fold. This was accomplished through the use of an agar plate screen incorporating the colony restrictor 2,6-dichloro-4-nitroaniline (dichloran) and the acid protease inhibitor diazoacetyl-norleucine methyl ester (DAN) to reduce high background concentrations of the native acid protease. A miniaturized liquid culture growth method using 24-well culture plates was an intermediate screen between agar plate and shake flask cultures. Analysis of broth samples for active calf chymosin was accomplished with a highly specific, 96-well microtiter plate turbidimetric assay.

Key words

Chymosin Acid protease Diazoacetyl-norleucine methyl ester Microculture Aspergillus awamori Heterologous protein 


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Copyright information

© Society for Industrial Microbiology 1990

Authors and Affiliations

  • Michael Lamsa
    • 1
  • Peggy Bloebaum
    • 1
  1. 1.Genencor, Inc.South San FranciscoUSA

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