Application of genomics in molecular breeding of the koji molds aspergillus oryzae and aspergillus sojae

Abstract

Recent results obtained from comparative genome analysis of koji molds, functional analysis of transcription factors and their application in breeding, and chromosomal engineering of the koji molds by deleting unessential chromosomal regions are presented. Comparative genome analysis of koji molds demonstrated genomic differences between Aspergillus oryzae and Aspergillus sojae. The number of putative protease genes, α-amylase genes, and glutaminase genes in A. oryzae was different from that in A. sojae. These differences may be responsible for different properties of the species because these genes play important roles in fermentation processes. Analysis of putative transcription factor genes of A. oryzae was conducted by disruption and overexpression of the genes. Several new genes implicated in conidiospore formation were discovered. We generated strains with minimized chromosomes using efficient gene-targeting techniques and large chromosomal deletion methods. As a result, a strain with a minimized chromosome 7 was constructed. Moreover, the strain with a minimized chromosome 7 was successfully fused with a strain with a reduced chromosome 8.