Isolation of a mutant with uninucleate conidia from Aspergillus oryzae and its use as a host strain.

K. Ishi, J. Maruyama, H. Nakajima and K. Kitamoto.


Aspergillus oryzae forms multinucleate conidia, which are considered to contribute to genetic stability in Japanese traditional food fermentation. However, this characteristic impedes the efficiency to isolate recessive mutants and homokaryotic transformants. We1) previously reported visualization of nuclei by expressing histone H2B-EGFP fusion protein in A. oryzae. We isolated multinucleate conidia deficient mutants (mun-) using FACS from H2B-EGFP expressing strain (niaD-, niaD::h2b-egfp) by UV irradiation. An isolated mutant, uni10 (niaD-, niaD::h2b-egfp, mun-), formed the highest percentage (approximately 80%) of uninucleate conidia. It showed almost the same phenotype in growth, conidiation and secretion of extra-cellular enzymes as the parent strain, suggesting that uni10 may be a useful host strain to isolate mutants and homokaryotic transformants. After curing of h2b-egfp from uni10 by positive selection method, an auxotrophic strain (niaD-, sC-,mun-) was bred and transformed with plasmids carrying each selection marker (niaD or sC) and heterologous genes. Therefore, it is expected that this strain can be used as a host in protein production. The efficiency of homokaryon formation after transformation will be discussed. 1) Maruyama J, et al. (2002). FEMS Microbiol Lett 206, 57-61

abstract No: 

Fungal Genet. Newsl. 50 (Supl):abstract

Full conference title: 

22nd Fungal Genetics Conference
    • Fungal Genetics Conference 22nd (2001)