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The disappearing periglacial ecosystem atop Mt. Kilimanjaro supports both cosmopolitan and endemic microbial communities.

ABSTRACT: Microbial communities have not been studied using molecular approaches at high elevations on the African continent. Here we describe the diversity of microbial communities from ice and periglacial soils from near the summit of Mt. Kilimanjaro by using both Illumina and Sanger sequencing of 16S and 18S rRNA genes. Ice and periglacial soils contain unexpectedly diverse and rich assemblages of Bacteria and Eukarya indicating that there may be high rates of dispersal to the top of this tropical mountain and/or that the habitat is more conducive to microbial life than was previously thought. Most bacterial OTUs are cosmopolitan and an analysis of isolation by geographic distance patterns of the genus Polaromonas emphasized the importance of global Aeolian transport in the assembly of bacterial communities on Kilimanjaro. The eukaryotic communities were less diverse than the bacterial communities and showed more evidence of dispersal limitations and apparent endemism. Cercozoa dominated the 18S communities, including a high abundance of testate amoebae and a high diversity of endemic OTUs within the Vampyrellida. These results argue for more intense study of this unique high-elevation "island of the cryosphere" before the glaciers of Kilimanjaro disappear forever.

SUBMITTER: Vimercati L

PROVIDER: S-EPMC6650471 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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The disappearing periglacial ecosystem atop Mt. Kilimanjaro supports both cosmopolitan and endemic microbial communities.

Vimercati Lara L Darcy John L JL Schmidt Steve K SK

Scientific reports 20190723 1

Microbial communities have not been studied using molecular approaches at high elevations on the African continent. Here we describe the diversity of microbial communities from ice and periglacial soils from near the summit of Mt. Kilimanjaro by using both Illumina and Sanger sequencing of 16S and 18S rRNA genes. Ice and periglacial soils contain unexpectedly diverse and rich assemblages of Bacteria and Eukarya indicating that there may be high rates of dispersal to the top of this tropical moun ...[more]

PMID: 31337772

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Project description:Photosynthetic bacteria from the class Chlorobia (formerly phylum Chlorobi) sustain carbon fixation in anoxic water columns. They harvest light at extremely low intensities and use various inorganic electron donors to fix carbon dioxide into biomass. Until now, most information on the functional ecology and local adaptations of Chlorobia members came from isolates and merely 26 sequenced genomes that may not adequately represent natural populations. To address these limitations, we analyzed global metagenomes to profile planktonic Chlorobia cells from the oxyclines of 42 freshwater bodies, spanning subarctic to tropical regions and encompassing all four seasons. We assembled and compiled over 500 genomes, including metagenome-assembled genomes (MAGs), single-amplified genomes (SAGs), and reference genomes from cultures, clustering them into 71 metagenomic operational taxonomic units (mOTUs or "species"). Of the 71 mOTUs, 57 were classified within the genus Chlorobium, and these mOTUs represented up to ∼60% of the microbial communities in the sampled anoxic waters. Several Chlorobium-associated mOTUs were globally distributed, whereas others were endemic to individual lakes. Although most clades encoded the ability to oxidize hydrogen, many lacked genes for the oxidation of specific sulfur and iron substrates. Surprisingly, one globally distributed Scandinavian clade encoded the ability to oxidize hydrogen, sulfur, and iron, suggesting that metabolic versatility facilitated such widespread colonization. Overall, these findings provide new insight into the biogeography of the Chlorobia and the metabolic traits that facilitate niche specialization within lake ecosystems.IMPORTANCE The reconstruction of genomes from metagenomes has helped explore the ecology and evolution of environmental microbiota. We applied this approach to 274 metagenomes collected from diverse freshwater habitats that spanned oxic and anoxic zones, sampling seasons, and latitudes. We demonstrate widespread and abundant distributions of planktonic Chlorobia-associated bacteria in hypolimnetic waters of stratified freshwater ecosystems and show they vary in their capacities to use different electron donors. Having photoautotrophic potential, these Chlorobia members could serve as carbon sources that support metalimnetic and hypolimnetic food webs.

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Dataset Information

The disappearing periglacial ecosystem atop Mt. Kilimanjaro supports both cosmopolitan and endemic microbial communities.

Publications

The disappearing periglacial ecosystem atop Mt. Kilimanjaro supports both cosmopolitan and endemic microbial communities.

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