Search

Copyright of Seikagaku Journal of Japanese Biochemical is the property of Japanese Biochemical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aspergillus oryzae produces important hydrolytic enzymes during the sake brewing process. The hydrolysates are used for alcoholic fermentation by sake yeast and affect the flavor of sake. Here, we isolated novel wild strains of A. oryzae and evaluated them for their potential as seed koji for sake to increase the diversity of A. oryzae strains for producing sake. Thirteen filamentous A. oryzae-like fungi were isolated from fields at the National Institute of Technology （KOSEN）, Nagaoka College and grown on rice-wood ash-potassium phosphate medium. All isolates were identified as A. oryzae using morphological characteristics, aflatoxin（ AF） production, DNA sequence analysis of the rDNA 5.8S-ITS region and AF biosynthesis homologous genes, and estimation of α-amylase gene copy number. Enzyme activities, which are important during sake brewing, were measured in rice koji prepared using each of the isolates and three control strains, including two commercial seed koji. The 13 isolates showed α-amylase and glucoamylase activities approximately equal to or higher than those of the two commercial seed koji, suggesting that the 13 isolates can be used as seed koji for sake. Furthermore, the production ratio of glucoamylase to α-amylase, one of the indices of high-quality koji, was higher in 12 isolates, except in the strain NKK9, than in the two commercial seed koji. Therefore, the 12 isolates described in this study could be used as seed koji for brewing high-quality sake. [ABSTRACT FROM AUTHOR]