Centre Sève, Département de Chimie, Université de Sherbrooke, J1K 2R1 Sherbrooke, QC, Canada.
Centre Sève, Département de Biologie, Université de Sherbrooke, J1K 2R1 Sherbrooke, QC, Canada.
Sci Total Environ. 2022 Sep 1;837:155761. doi: 10.1016/j.scitotenv.2022.155761. Epub 2022 May 6.
Feather mosses are abundant cryptogams of the boreal forest floor and shelter a broad diversity of bacteria who have important ecological functions (e.g., decomposition, nutrient cycling). In particular, nitrogen (N-) fixation performed by feather moss-associated diazotrophs constitutes an important entry of nitrogen in the boreal forest ecosystem. However, the composition of the feather moss bacteriome and its environmental drivers are still unclear. Using cDNA amplicon sequencing of the 16S rRNA and nifH genes and cyanobacterial biomass quantification, we explored the active global and diazotrophic bacterial communities of two dominant feather moss species (i) at the ecosystem scale, along a 500-km climatic and nutrient deposition gradient in the North American boreal forest, and (ii) at the plant scale, along the moss shoot senescence gradient. We found that cyanobacteria were major actors of the feather moss bacteriome, accounting for 33% of global bacterial communities and 65% of diazotrophic communities, and that several cyanobacterial and methanotrophic genera were contributing to N-fixation. Moreover, we showed that bacteria were occupying ecological niches along the moss shoot, with phototrophs being dominant in the apical part and methanotrophs being dominant in the basal part. Finally, climate (temperature, precipitation), environmental variables (moss species, month, tree density) and nutrients (nitrogen, phosphorus, molybdenum, vanadium, iron) strongly shaped global and diazotrophic bacteriomes. In summary, this work presents evidence that the feather moss bacteriome plays crucial roles in supporting moss growth, health, and decomposition, as well as in the boreal forest carbon and nitrogen cycles. This study also highlights the substantial effects of climate and nutrients on the feather moss bacteriome, suggesting the importance of understanding the impacts of global change on moss-associated bacterial growth and activity.
羽藓是北方森林地表丰富的隐花植物，为具有重要生态功能的多种细菌提供庇护（例如，分解、养分循环）。特别是羽藓相关固氮菌进行的氮（N）固定构成了北方森林生态系统中氮的重要输入。然而，羽藓细菌组的组成及其环境驱动因素仍不清楚。本研究通过对 16S rRNA 和 nifH 基因的 cDNA 扩增子测序和蓝细菌生物量定量，我们从两个方面探索了两个主要羽藓物种的活跃全球和固氮细菌群落：（i）在生态系统尺度上，沿着北美北方森林的 500 公里气候和养分沉积梯度；（ii）在植物尺度上，沿着藓枝衰老梯度。结果发现，蓝细菌是羽藓细菌组的主要组成部分，占全球细菌群落的 33%和固氮细菌群落的 65%，并且几个蓝细菌和甲烷氧化菌属参与了固氮。此外，我们表明，细菌在藓枝上占据生态位，在顶端部分以自养生物为主，在基部部分以甲烷氧化菌为主。最后，气候（温度、降水）、环境变量（藓种、月份、树木密度）和养分（氮、磷、钼、钒、铁）强烈塑造了全球和固氮细菌组。总之，本研究证明了羽藓细菌组在支持藓生长、健康和分解以及北方森林碳氮循环方面发挥着重要作用。本研究还强调了气候和养分对羽藓细菌组的巨大影响，表明了理解全球变化对藓相关细菌生长和活性的影响的重要性。
