Abstract
BackgroundLake Baikal is the largest body of liquid freshwater on Earth. Previous studies have described the microbial composition of this habitat, but the viral communities from this ecosystem have not been characterized in detail.ResultsHere, we describe the viral diversity of this habitat across depth and seasonal gradients. We discovered 19,475 bona fide viral sequences, which are derived from viruses predicted to infect abundant and ecologically important taxa that reside in Lake Baikal, such as Nitrospirota, Methylophilaceae, and Crenarchaeota. Diversity analysis revealed significant changes in viral community composition between epipelagic and bathypelagic zones. Analysis of the gene content of individual viral populations allowed us to describe one of the first bacteriophages that infect Nitrospirota, and their extensive repertoire of auxiliary metabolic genes that might enhance carbon fixation through the reductive TCA cycle. We also described bacteriophages of methylotrophic bacteria with the potential to enhance methanol oxidation and the S-adenosyl-L-methionine cycle.ConclusionsThese findings unraveled new ways by which viruses influence the carbon cycle in freshwater ecosystems, namely, by using auxiliary metabolic genes that act upon metabolisms of dark carbon fixation and methylotrophy. Therefore, our results shed light on the processes through which viruses can impact biogeochemical cycles of major ecological relevance.B3i_F4qvBy9xmcnWBwjShqVideo
Highlights
Lake Baikal is the largest body of liquid freshwater on Earth
Depth variations of archaeal and bacterial communities in Lake Baikal We have analyzed a total of ten metagenomes sequenced from different habitats of Lake Baikal
We sought to describe the depth variations of prokaryotic community composition of Lake Baikal based on taxonomic profiles derived from metagenomes from winter and summer
Summary
Lake Baikal is the largest body of liquid freshwater on Earth. Lake Baikal is the largest and deepest lake on Earth [1, 2]. The surface of Lake Baikal freezes during winter, so that below the ice layer water temperatures approach 0 °C while towards deeper waters temperature raises slightly to a maximum of 4 °C. The ice layer melts, and surface water temperature raises to nearly 12 °C, only to decrease rapidly towards deeper waters (below 50 m) to the same 4 °C that are kept all year around for the deep water mass. Recent metagenomic studies have analyzed the microbiome of sub-ice epipelagic and bathypelagic waters, revealing the key microbes that dwell at this ecosystem as well as the ecological processes in which
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
