Improvement of Enzyme Productivities through Mutation or Haploidization of Heterozygous Diploids Obtained by Protoplast-fusion of Aspergillus sojae

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概要

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• A new breeding process for Aspergillus sojae involving protoplast fusion was studied to obtain more desirable koji-molds for soy-sauce production, especially as to their enzyme productivities. A pair of double-marker mutants with characteristic enzyme-productivities, derived from genealogically unrelated A. sojae cultures, were fused by means of the protoplast fusion technique. The fusants were UV-treated, and stable heterozygous diploids were obtained. Further improvement of their enzyme-productivities was attempted using two approaches. Through the usual mutation of the heterozygous diploids, the activities of protease and glutaminase were simultaneously improved to a certain extent. Through the haploidization of the heterozygous diploids with benomyl or p-fluorophenylalanine (FPA), some haploids considered phenotypically to be recombinants were segregated, in addition to a large number of haploids that had reverted to the original double marker mutants. On screening these haploid-recombinants, the authors obtained a few more excellent recombinants, as to their enzyme productivities, that is, strains producing as much protease as the hyper-protease producer and producing almost as much glutaminase as the hyperglutaminase producing parent. It has been shown that mutation or especially haploidization of heterozygous diploids produced by cell-fusion could be a very useful technique for the breeding of new industrial koji-molds.

• 社団法人 日本農芸化学会の論文

著者

• Uchida Kinji

  Soy Sauce Research Laboratories Kikkoman Corp.

• USHIJIMA Shigeomi

  Soy Sauce Research Laboratory, Kikkoman Corp.

• Nakadai Tadanobu

  Soy Sauce Research Laboratory Kikkoman Corp.

• Ushijima Shigeomi

  Soy Sauce Research Laboratory Kikkoman Corp.

関連論文

• Preparation of Phage-insensitive Strains of Tetragenococcus halophila and Its Application for Soy Sauce Fermentation
• Aspartate Decarboxylation Encoded on the Plasmid in the Soy Sauce Lactic Acid Bacterium, Tetragenococcus halophila D10
• Interspecific Electrofusion of Protoplasts between Aspergillus oryzae and Aspergillus sojae(Microbiology & Fermentation Industry)
• Further Evidence on the Interspecific Protoplast Fusion between Aspergillus oryzae and Aspergillus sojae and Subsequent Haploidization, with Special Reference to Their Production of Some Hydrolyzing Enzymes(Microbiology & Fermentation Industry)
• Breeding of New Koji-molds through Interspecific Hybridization between Aspergillus oryzae and Aspergillus sojae by Protoplast Fusion(Microbiology & Fermentation Industry)
• NADH Dehydrogenase Activity of Pediococcus halophilus as a Factor Determining its Reducing Force(Microbiology & Fermentation Industry)
• Breeding by Protplast Fusion of Koji Mold, Aspergillus sojae(Microbiology & Fermentation Industry)
• Improvement of Enzyme Productivities through Mutation or Haploidization of Heterozygous Diploids Obtained by Protoplast-fusion of Aspergillus sojae
• Oxygen Consumption by Pediococcus halophilus

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