We examined factors shaping community assembly of the bull kelp (Nereocystis luetkeana) microbiome by comparing microbial biofilm formation on photosynthetic kelp blade tissues and artificial kelp substrates (‘agar substrates’) deployed into a kelp forest. New kelp blade tissues were colonized by markedly distinct microbial taxa relative to agar substrates during the same time interval, even when agar substrates were infused with N. luetkeana blades, suggesting that microbial settlement onto kelp surfaces is more than just attraction to a polysaccharide‐rich surface. Further, common seawater taxa such as Colwellia sp. and Psychromonas sp. became abundant on agar substrates but avoided new kelp blade tissues, indicating that host‐specific factors may deter certain surface‐associated marine microbial taxa. Over two‐thirds of the bacterial taxa in the kelp microbiome were associated with strictly aerobic metabolisms; thus, photosynthetic production of O₂ may favour aerobic microbial metabolisms. While living kelp blades primarily recruited aerobic microbes, including the obligate aerobe Granulosicoccus sp., microbes that colonized agar substrates were predominantly facultative anaerobes. We also found that infusion of kelp tissues into agar substrates altered microbial community composition and lowered taxonomic diversity relative to control agar substrates, suggesting that non‐living components of the kelp blade also impact microbial community assembly.

中文翻译：

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与人造海带基质相比，氧代谢影响光合海带叶片上的微生物沉降


我们通过比较光合海带叶片组织和部署在海带森林中的人造海带基质（“琼脂基质”）上的微生物生物膜形成，研究了影响公牛海带（ Nereocystis luetkeana ）微生物组群落组装的因素。在同一时间间隔内，新的海带叶片组织被相对于琼脂基质明显不同的微生物类群定殖，即使琼脂基质注入了海藻叶片，这表明微生物在海带表面的沉降不仅仅是对富含多糖的吸引表面。此外，常见的海水类群如Colwellia sp 。和Psychromonas sp 。在琼脂基质上变得丰富，但避免了新的海带叶片组织，表明宿主特异性因素可能会阻止某些与表面相关的海洋微生物类群。海带微生物组中超过三分之二的细菌类群与严格的有氧代谢相关。因此，光合作用产生的O ₂可能有利于微生物的需氧代谢。虽然活海带叶片主要招募需氧微生物，包括专性需氧微生物颗粒球菌，但在琼脂基质上定殖的微生物主要是兼性厌氧微生物。我们还发现，将海带组织注入琼脂基质中会改变微生物群落组成，并降低相对于对照琼脂基质的分类多样性，这表明海带叶片的非生命成分也会影响微生物群落的组装。