Transformation of Aspergillus oryzae through Plasmid-mediated Complementation of the Methionine-auxotrophic Mutation(Microbiology & Fermentation Industry)

概要

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A methionine-auxotrophic mutant (Met^-) of aspergillus oryzae was transformed to prototrophy (Met^+) with plasmid pKA5-1 carrying a 3.5 Kbp genomic DNA fragment of A.oryzae through treatment of spheroplasts with polyethylene glycol 4000 and CaCl_2. The highest transformation frequency obtained was 32 transformants per μg DNA. We recovered the transforming plasmid from the Met^+ transformant cell, showing that this plasmid was derived from the original plasmid, pKA5-1. The mitotic stability of the Met^+ transformant was about 70% after growth without selective pressure; the transforming DNA was lost in the Met^- clone. These findings suggest that the transforming plasmid, pKA5-1, exists in the transformant cell as a self-replicating circular DNA. The gene in the 3.5 Kbp DNA fragment, which complements the methionine-auxotrophic mutation, can be used as a selectable marker to construct efficient plasmid vectors for A.oryzae
社団法人日本農芸化学会の論文
1987-02-23