チーズ上の菌類が進化の分子メカニズムを解明(Cheese Fungi Help Unlock Secrets of Evolution)

2025-09-12 タフツ大学

タフツ大学の研究チームは、バーモント州のチーズ熟成洞窟で「進化を目撃した」事例を報告した。チーズの表面に生えるカビ Penicillium solitum が、数年の間に緑色から白色へと変化していたのである。遺伝子解析の結果、この色の変化は alb1遺伝子の破壊によるメラニン合成経路の停止が原因と判明。洞窟という暗環境では紫外線防御のためのメラニンが不要となり、代謝コスト削減のため色素を作らなくなったと解釈された。これはエネルギー節約の戦略的進化の一例である。研究は Current Biology に掲載され、農業や食品分野への応用可能性も指摘される。例えば、世界の作物の約20%は収穫前に、さらに20%は収穫後にカビによって失われており、真菌の適応メカニズムを理解することは食料安全保障の課題解決につながる。

<関連情報>

北米チーズ洞窟の長期モニタリングが明らかにした菌類適応のメカニズムと結果 Long-term monitoring of a North American cheese cave reveals mechanisms and consequences of fungal adaptation

Nicolas L. Louw ∙ Justin L. Eagan ∙ Jackson Larlee ∙ Mateo Kehler ∙ Nancy P. Keller ∙ Benjamin E. Wolfe
Current Biology  Published:September 12, 2025
DOI:https://doi.org/10.1016/j.cub.2025.08.053

Graphical abstract

チーズ上の菌類が進化の分子メカニズムを解明(Cheese Fungi Help Unlock Secrets of Evolution)

Highlights

  • A Penicillium solitum population has shifted from green to white in a cheese cave
  • Multiple mutations in a melanin biosynthesis gene (alb1) are found in white strains
  • White P. solitum strains outcompete green strains, but only in the dark
  • This local adaptation may be part of a fungal domestication process

Summary

Previous comparative and experimental evolution studies have suggested how fungi may rapidly adapt to new environments, but direct observation of in situ selection in fungal populations is rare due to challenges with tracking populations over human time scales. We monitored a population of Penicillium solitum over eight years in a cheese cave and documented a phenotypic shift from predominantly green to white strains. Diverse mutations in the alb1 gene, which encodes the first protein in the dihydroxynaphthalene (DHN)-melanin biosynthesis pathway, explained the green-to-white shift. A similar phenotypic shift was recapitulated with an alb1 knockout and experimental evolution in laboratory populations. The most common genetic disruption of the alb1 genomic region was caused by putative transposable element insertions upstream of the gene. White strains had substantial downregulation in global transcription, with genetically distinct white strains possessing divergent shifts in the expression of different biological processes. White strains outcompeted green strains in co-culture, but this competitive advantage was only observed in the absence of light. Our results illustrate how fermented food production by humans provides opportunities for relaxed selection of key fungal traits over short time scales. The local adaptation we observed may be part of a domestication process that could provide opportunities to generate new strains for innovation in fermented food production.

1202農芸化学
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