2025-09-23 筑波大学
図 (a)麹菌と関連する種を生育させたプレート。(b)細い菌糸(4 mm幅)から太い菌糸(12 mm幅)が分岐で出現する。核内のヒストン(染色体を構成するタンパク質)を蛍光タンパク質(GFP)で標識した。 (c)Aspergillus属糸状菌の菌糸の先端の細胞とそこに含まれる核(GFPまたは蛍光染色)の分布(スケールバーは10 mm)。(d)分岐の形成時に、細胞体積と核数の増加が同時に起きるモデル。細胞体積と核の数は互いに制御し合う。(e)細胞体積と核数が増加することの利点と欠点、および、麹菌の育種との関わり。
<関連情報>
- https://www.tsukuba.ac.jp/journal/biology-environment/20250923160000.html
- https://www.tsukuba.ac.jp/journal/pdf/p20250923160000.pdf
- https://elifesciences.org/articles/107043
麹菌Aspergillus oryzaeにおける細胞体積と核数の増加がその高い酵素生産に寄与する The increase in cell volume and nuclear number of the koji-fungus Aspergillus oryzae contributes to its high enzyme productivity
Ayaka Itani,Haruto Motomura,Ken Oda,Hideyuki Yamashita,Kanae Sakai,Ken-ichi Kusumoto,Shinsuke Shigeto,Takehiko Ichikawa,Hosain Mohammad Mubarak,…,Norio Takeshita
eLife Published:Sep 23, 2025
DOI:https://doi.org/10.7554/eLife.107043.4
Abstract
While the ratio of nuclei to cell volume is well regulated, it remains largely unexplored in multinucleate organisms. The koji-fungus Aspergillus oryzae, traditionally used in Japanese brewing and fermentation for over a thousand years, is now widely utilized in modern biotechnology as a host for enzyme production. We discovered that, over time in culture, hyphae become thicker, resulting in a tenfold increase in cell volume, and the number of nuclei in hyphal cells also increases tenfold, exceeding 200. The increase in cell volume and nuclear number is unique among the investigated Aspergillus species and correlates with its high enzyme production capabilities. Since nuclear number and cell volume are correlated, both must increase simultaneously for either to expand. Our analyses identified genetic factors and nutritional environmental signals involved in each of these increases. Increases in nuclear number and cell volume were also observed in other fungi bred for industrial use. This study not only deepens our understanding of the evolutionary processes that promote high enzyme productivity through fungal breeding, but also provides insights into the molecular mechanisms regulating cell volume and nuclear number in multinucleate organisms.
