Methane-Oxidizing Activity and Phylogenetic Diversity of Aerobic Methanotrophs in the Laptev Sea Upper Sediment Horizons

• Published in: Microbiology (New York) 2021-05, Vol.90 (3), p.314-323
• Main Authors: Tikhonova, E. N., Kadnikov, V. V., Rusanov, I. I., Beletsky, A. V., Zakharova, E. E., Samylina, O. S., Ravin, N. V., Pimenov, N. V.
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Carbon dioxide; Experimental Articles; Freshwater ecosystems; Life Sciences; Medical Microbiology; Methane; Methanotrophic bacteria; Microbiology; Microorganisms; Oxidation; Phylogenetics; Phylogeny; rRNA 16S; Sediments
• ISSN: 0026-2617; 1608-3237
• DOI: 10.1134/S0026261721030127

— Methane oxidation rates and diversity of methane-oxidizing microorganisms were studied in the upper sediment layers of the Laptev Sea (methane seep area, Lena fore-delta, shelf, and upper slope not affected by seeps and river flow). The highest methane concentrations and methane oxidation rates (up to 1.16 µmol СН 4 dm −3 day −1 ) were revealed at the seep stations. Carbon dioxide was the main product of methane oxidation at all stations. Sequencing of the 16S rRNA gene fragments revealed microorganisms of the class Gammaproteobacteria , order Methylococcales . Since the share of methanotrophs was high at the sites of constant gas seepage (up to 1.93% of the total read number), they could be detected by sequencing of the native samples. Phylogenetic diversity of methane-oxidizing bacteria was not high, and all detected microorganisms belonged to the Deep-Sea 1 cluster. On the phylogenetic tree, the sequences formed a cluster together with the genus Methyloprofundus. Members of the genera Methylomonas and Methylobacter related to methanotrophs inhabiting freshwater ecosystems were revealed in enrichments from the coastal stations sediment samples.