Genomic Analysis of Koji Mold Aspergillus oryzae and Investigation of Novel Peptidases by Post-genomic Approach

Abstract

Aspergillus oryzae is a filamentous fungus used as a starter microorganism in the process of manufacturing various kinds of traditional fermented food. It is also used as a producer of enzymes for both food processing and pharmaceuticals, such as proteases and taka-amylase. In order to clarify the function of this microorganism in fermentation industries and utilize the new function of A. oryzae, it was subject to genomic analysis. During the analysis, the telomere of A. oryzae exhibited a novel repeated sequence distinct from other fungi. Genomic analysis also revealed that the genome of A. oryzae consists of eight chromosomes containing 12,074 genes and is larger in size than Aspergillus nidulans and Aspergillus fumigatus. A. oryzae contains sequences specific for A. oryzae for genes involved in primary and secondary metabolism, when compared with A. nidulans and A. fumigatus. Among them, the function of one of the peptidase-like gene products was investigated with a post-genomic approach, and determined as an aminopeptidase specific for acidic amino acids (aspartate and glutamate) which was first identified in filamentous fungi. It also demonstrated that the addition of cobalt ion to the growth medium greatly improved the specific activity. Using the same approach, some of the novel aminopeptidases and carboxypeptidases of A. oryzae were identified and characterized.