Abstract
Simple SummaryThe Kuril Islands are a part of the Circum-Pacific Belt of volcanoes and have many hot springs. Nonetheless, due to the border regime, these islands are difficult to access, and microbial communities of the geothermal springs of these islands have hardly been studied microbiologically and have not been studied metagenomically at all. Here we conducted the first metagenomic study on two thermophilic microbial communities of Kunashir Island. Faust Lake is hot (48 °C) and highly acidic (pH 2.0), whereas the Tretyakovsky Thermal Spring is also hot (52 °C) but weakly acidic (pH 6.0). We demonstrated that water pH affects the composition of the microbial communities.The Kuril Archipelago is a part of the Circum-Pacific Belt (Ring of Fire). These islands have numerous thermal springs. There are very few studies on these microbial communities, and none of them have been conducted by modern molecular biological methods. Here we performed the first metagenomic study on two thermophilic microbial communities of Kunashir Island. Faust Lake is hot (48 °C) and highly acidic (pH 2.0). We constructed 28 metagenome-assembled genomes as well as 17 16S ribosomal RNA sequences. We found that bottom sediments of Faust Lake are dominated by a single species of red algae belonging to the Cyanidiaceae family. Archaeans in Faust Lake are more diverse than bacteria but less abundant. The Tretyakovsky Thermal Spring is also hot (52 °C) but only weakly acidic (pH 6.0). It has much higher microbial diversity (233 metagenome-assembled genomes; 93 16S ribosomal RNAs) and is dominated by bacteria, with only several archaeans and one fungus. Despite their geographic proximity, these two thermal springs were found to not share any species. A comparison of these two lakes with other thermal springs of the Circum-Pacific Belt revealed that only a few members of the communities are shared among different locations.
Highlights
Microorganisms, especially prokaryotes, are capable of living in diverse environments, which may strongly differ from those present on the surface of the Earth in such parameters as temperature, pH, redox potential, and availability of organic matter and light
As a result of the processing, 1,235,736 (0.6% of the initial number of reads) and 148,563 (0.035% of the initial number of reads) reads were lost in the Faust Lake (FAU) and Tretyakovsky Spring (TRT) datasets, respectively
We performed the first metagenomic analysis of thermal springs of Kunashir Island. This is the first step in closing the gap in such studies on the Kuril Islands
Summary
Microorganisms, especially prokaryotes, are capable of living in diverse environments, which may strongly differ from those present on the surface of the Earth in such parameters as temperature, pH, redox potential, and availability of organic matter and light. Extremophiles living at high temperatures have turned out to be some of the most promising as sources of new enzymatic activities for molecular biology and biotechnology. Their taxonomic diversity is the second most important parameter: these communities are reported to contain new species and phyla that have not been found at mesophilic sites. Metagenomics allows one to investigate taxonomic diversity and metabolic properties of communities without their cultivation This is relevant for thermophiles, which are notoriously resilient to cultivation in the laboratory. Many of those are known only by their DNA sequences [3]. They are intensively studied due to their peculiar chemical composition and high value for applied research [4]
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