Principal Investigator Université de Sherbrooke, Canada
Background/Question/Methods Interactions between mosses and their associated microbiomes contribute substantially to boreal ecosystem processes. While moss-cyanobacteria interactions are very well studied, mosses harbour an array of microbial species that facilitate nitrogen cycling, as well as organic matter decomposition, carbon storage and phosphorus cycling. Current research indicates that local environmental variables such as temperature, moisture, shade, leaf-litter presence and host moss species impact moss microbiome communities. Previous studies also allude to moss microbiome differences between the photosynthetically active green zones and decaying brown zones of mosses. Unfortunately, further moss microbiome studies have not fully explored these variables. Present moss microbiome research tends to focus on taxonomic diversity, with microbiome functions being inferred. Hence, various metabolic pathways and functional genes of the moss microbiome remain unknown or poorly described. The objective of the current project was to investigate the functional diversity of 7 boreal moss species from the Eeyou Istchee region of Quebec and 3 moss species from Alaska via shotgun sequencing. Moss samples from Eeyou Istchee were separated into green and brown zones to investigate interspatial functional differences. This project also uses the latest metagenomic processing infrastructure and pipelines to update existing reference databases obtained from the Alaskan moss microbiome.
Results/Conclusions The bacterial community structure of Alaskan mosses has been previously classified via 16S amplicon sequencing. Using the Kraken database, a diverse array of fungi and archaea is revealed across all samples. Of note are the presence of archaea from the taxa Halobacteria and Methanomicrobia, as well as from the families Nitrosopumilaceae and Nitrosphaeraceae – all taxa associated with nitrogen fixation. The presence of fungal taxa ranged from plant root-associated Heliotales, to more litter-associated Dothideomycetes and Chaetomiaceae. It does not appear that archaea makes a significant contribution to ecosystem functions such as organic matter degradation. However, this early stage metagenomic analysis reveals that approximately 98% of reads were unattributable to a particular pathway or associated with specific taxa. While the nitrogen-fixing capabilities of cyanobacteria have been well understood, it was interesting to note this phylum’s involvement in other pathways such as degradation of carbon-based compounds, vitamin biosynthesis and molybdenum and sulfur uptake pathways. Furthermore, it also appears that taxa within the Proteobacteria lineage were significant contributors to carbon fixating pathways such as the Calvin cycle. This concurs with results from previous studies that reveal the functional significance of Proteobacteria as part of the moss microbiome.