Host: Japanese Sciety for Food Science and Technology
Name : The 72nd Annual Meeting of JSFST
Number : 72
Location : [in Japanese]
Date : August 27, 2025 - August 29, 2025
Pages 19-
Jun-ichi Maruyama, PhD
Professor, Graduate School of Agricultural and Life Sciences, The University of Tokyo
He acquired Ph.D. from Graduate School of Agricultural and Life Sciences, The University of Tokyo (2001) and then continued postdoctoral research. He was appointed as Assistant Professor (2006) at The University of Tokyo, and during it he also studied as a guest researcher at Georg August University Göttingen, Germany (2010). He became Project Associate Professor (2016), Project Professor (2021), and then Professor (2025) at The University of Tokyo.
Koji mold is a microorganism used in Japanese traditional brewing industry, and its importance was recognized again in the registration of "Traditional Sake Brewing" on the UNESCO Intangible Cultural Heritage list in 2024. Koji mold is also used to produce enzymes and proteins/natural products derived from different organisms, and recently the fungus itself has attracted attention as an edible protein source.
Research on koji mold has made great progress since the first whole genome sequence was deciphered in 2005. With the development of technology that enables highly efficient genetic manipulation, functional analysis and functional development of many genes have been actively carried out. For an example, the authors have been conducting functional analysis of genes in the intracellular organelles of koji mold, and in the process discovered for the first time that peroxisomes are involved in the biosynthesis of biotin, one of vitamins. This discovery led to the idea of developing an amazake, in which vitamins produced by koji mold play an important role, and it was released as "Doctor's Old Koji Amazake" using koji mold strains that Dr. Kinichiro Sakaguchi, Professor Emeritus of The University of Tokyo, known as the “God of Sake”, had collected before or during Pacific War.
On the other hand, the genetic manipulation of koji mold as described above has been carried out mainly on the RIB40 strain, the first whose whole genome sequence was deciphered. In fact, there are a wide variety of industrial strains of koji mold suitable for various purposes, such as sake, soy sauce, miso, and genetic manipulation of these industrial strains has been extremely difficult and inefficient. With the genome editing technology CRISPR/Cas9 system, the efficiency of gene manipulation in industrial koji mold strains was dramatically improved, also enabling multiple gene modifications. By modifying the metabolism of koji mold on a large scale, metabolic production capability was significantly improved, demonstrating that these approaches are effective in developing functions to greatly explore the potential of koji mold.
In recent years, with the development of next-generation sequencing technology, the deciphering of the genome sequences of many industrial strains of koji mold has been reported. Analysis using genome editing technology based on the results of comparative genome analysis has allowed us to link the diverse characteristics and gene functions of industrial koji mold strains that have been specialized for various uses. Furthermore, it is expected that the breeding and development of koji mold aimed at true industrial use will become possible by performing efficient and flexible genetic modifications of strains with industrially excellent properties.
In addition to the background of koji mold having been used for many years in the brewing industry in Japan, there is growing interest in its use in new industrial fields and even overseas. It is expected that the potentials of koji mold will be maximized by combining traditional knowledge and advanced technology, which will lead to the creation of diverse new food industries and cultures.
