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Research article - Peer-reviewed, 2021

Vertical stratification patterns of methanotrophs and their genetic controllers in water columns of oxygen-stratified boreal lakes

Rissanen, Antti J.; Saarela, Taija; Jantti, Helena; Buck, Moritz; Peura, Sari; Aalto, Sanni L.; Ojala, Anne; Pumpanen, Jukka; Tiirola, Marja; Elvert, Marcus; Nykanen, Hannu

Abstract

The vertical structuring of methanotrophic communities and its genetic controllers remain understudied in the water columns of oxygen-stratified lakes. Therefore, we used 16S rRNA gene sequencing to study the vertical stratification patterns of methanotrophs in two boreal lakes, Lake Kuivajarvi and Lake Lovojarvi. Furthermore, metagenomic analyses were performed to assess the genomic characteristics of methanotrophs in Lovojarvi and the previously studied Lake Alinen Mustajarvi. The methanotroph communities were vertically structured along the oxygen gradient. Alphaproteobacterial methanotrophs preferred oxic water layers, while Methylococcales methanotrophs, consisting of putative novel genera and species, thrived, especially at and below the oxic-anoxic interface and showed distinct depth variation patterns, which were not completely predictable by their taxonomic classification. Instead, genomic differences among Methylococcales methanotrophs explained their variable vertical depth patterns. Genes in clusters of orthologous groups (COG) categories L (replication, recombination and repair) and S (function unknown) were relatively high in metagenome-assembled genomes representing Methylococcales clearly thriving below the oxic-anoxic interface, suggesting genetic adaptations for increased stress tolerance enabling living in the hypoxic/anoxic conditions. By contrast, genes in COG category N (cell motility) were relatively high in metagenome-assembled genomes of Methylococcales thriving at the oxic-anoxic interface, which suggests genetic adaptations for increased motility at the vertically fluctuating oxic-anoxic interface.

Keywords

methanotroph; Methylococcales; vertical structuring; 16S rRNA; metagenomics; genetic potential

Published in

FEMS Microbiology Ecology
2021, volume: 97, number: 2, article number: fiaa252
Publisher: OXFORD UNIV PRESS

Authors' information

Rissanen, Antti J.
Tampere University
Saarela, Taija
University of Eastern Finland
Jantti, Helena
University of Eastern Finland
Uppsala University
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Peura, Sari
Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology
Aalto, Sanni L.
University of Eastern Finland
Aalto, Sanni L.
University of Jyvaskyla
Ojala, Anne
University of Helsinki
Pumpanen, Jukka
University of Eastern Finland
Tiirola, Marja
University of Jyvaskyla
Elvert, Marcus
University of Bremen
Nykanen, Hannu
University of Eastern Finland

UKÄ Subject classification

Genetics
Ecology

Publication Identifiers

DOI: https://doi.org/10.1093/femsec/fiaa252

URI (permanent link to this page)

https://res.slu.se/id/publ/111764