海洋細菌と腸内細菌の関連性を発見（Related bacteria in the ocean and the gut）

2026-05-13

2026-05-11 マックス・プランク研究所

マックス・プランク海洋微生物学研究所の研究チームは、海洋に生息する細菌と人間の腸内細菌に、進化的に近縁なグループが存在することを明らかにした。研究では、大規模なゲノム解析を用いて海洋細菌と腸内細菌の系統関係や代謝機能を比較。その結果、一見まったく異なる環境に生息する細菌同士でも、共通祖先を持ち、栄養利用や有機物分解に関わる類似機能を共有していることが判明した。特に、酸素の少ない環境で生きるための代謝戦略や、複雑な有機化合物を分解する能力に共通点が見られた。研究は、微生物進化が環境を越えてどのように適応してきたかを示すとともに、海洋生態系とヒト健康研究を結びつける新たな視点を提供する成果となった。また、腸内細菌研究で得られた知見を海洋微生物学へ応用できる可能性も示されている。

An almost perfect match: Two protein subunit structures, one from a gut bacterium and one from a marine relative, overlaid on top of each other. The striking overlap reveals how conserved this protein is across environments. © MPI f. Marine Microbiology/ Isabella Wilkie

＜関連情報＞

保存されたグリカン利用戦略が、水生生態系と腸内生態系におけるアッケルマンシア科の成功を形作っている Conserved glycan-utilization strategies shape Akkermansiaceae success across aquatic and gut ecosystems

Isabella Wilkie,Nicole Von Possel,Tomás Sauma-Sánchez,Greta Reintjes,Luis H Orellana
The ISMA Journal Published:22 April 2026
DOI:https://doi.org/10.1093/ismejo/wrag096

Abstract

Elucidating interaction mechanisms and substrate specialization is central to understanding bacterial adaptation across ecological niches. Specialized mucin-degrading bacteria of the genus Akkermansia are widely recognized for their beneficial roles in the human gut, yet it remains unclear whether this specialization is unique to the gut or reflects a conserved ecological strategy across different hosts and environments. Here, we show that members of the family Akkermansiaceae share a deeply conserved genetic and mechanistic framework enabling colonization across gut and aquatic ecosystems. Comparative genomics of Akkermansiaceae representatives revealed niche-specific gene repertoires tightly adapted to substrate source and availability. Marine representatives encode distinct combinations of CAZymes and comparatively expanded sulfatase repertoires that enable the degradation of sulfated polysaccharides such as fucoidan, a recalcitrant substrate linked to carbon sequestration. Structural predictions and comparisons identified a conserved molecular system centered on a type IV–like pilus that mediates attachment to complex, fucose-rich glycans. The genes underlying this system are syntenic with the recently described mucin utilization locus in Akkermansia muciniphila, revealing an evolutionary continuity between aquatic and gut lineages. Seawater incubations with fluorescently labeled substrates confirmed fucoidan uptake and degradation by marine Akkermansiaceae. Together, these results reveal a unified glycan-utilization strategy spanning the environmental breadth of Akkermansiaceae and provide a mechanistic framework linking ecological success in marine environments to traits associated with probiotic functions in the human gut.