Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient Intake

In an aquatic ecosystem, the supply of nutrients is essential for the biogeochemical cycle, and it affects the taxonomic composition of the microbial communities. Here, by using high-throughput sequencing (HTS) of the 16S and 18S rRNA gene fragments, we compared free-living (FL) and particle-associa...

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Main Authors: Maria Bashenkhaeva, Yelena Yeletskaya, Irina Tomberg, Artyom Marchenkov, Lubov Titova, Yuri Galachyants
Format: Article
Language:English
Published: MDPI AG 2023-04-01
Series:Diversity
Subjects:
Online Access:https://www.mdpi.com/1424-2818/15/4/572
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author Maria Bashenkhaeva
Yelena Yeletskaya
Irina Tomberg
Artyom Marchenkov
Lubov Titova
Yuri Galachyants
author_facet Maria Bashenkhaeva
Yelena Yeletskaya
Irina Tomberg
Artyom Marchenkov
Lubov Titova
Yuri Galachyants
author_sort Maria Bashenkhaeva
collection DOAJ
description In an aquatic ecosystem, the supply of nutrients is essential for the biogeochemical cycle, and it affects the taxonomic composition of the microbial communities. Here, by using high-throughput sequencing (HTS) of the 16S and 18S rRNA gene fragments, we compared free-living (FL) and particle-associated (PA) bacterial communities and microeukaryotic communities in the areas with different nutrient intakes in freshwater Lake Baikal during the ice-covered and summer periods. Samples were taken at the inflow of the Selenga River, which is the main tributary of the lake, and at several established coastal research stations. The metabolic potential of the bacterial communities was predicted using PICRUSt. Differences were found in both FL and PA communities of the river mouth compared to the photic zone of the lake. The composition of FL communities was significantly different between the sampling sites in the ice-covered period, which is most likely influenced by different hydrochemical conditions. In contrast, the PA communities were more similar during the ice-covered period, but they changed considerably from spring to summer and their diversity increased. The diversity of the microeukaryotic communities also increased in summer, which may have contributed to the increase in bacterial diversity. In co-occurrence networks analysis, the number of interconnected bacterial OTUs in FL exceeded those for PA. The FL communities were dominated by <i>Actinobacteriota</i>, while the major PA OTUs belonged to a mixed cluster, which were mainly assigned to the phyla <i>Bacteroidota</i> and <i>Verrucomicrobiota</i>. As a result, PA communities were enriched in pathways responsible for the metabolism of sulfur, fucose, cellulose and urea. Our results confirm the difference between the FL and PA bacterial communities in Lake Baikal. These results also highlight the complex pattern of interactions between bacteria and microeukaryotes in a natural freshwater ecosystem across spatial and temporal scales.
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spelling doaj.art-f76dff69f65a45d4a30d7a42fa78be802023-11-17T18:57:30ZengMDPI AGDiversity1424-28182023-04-0115457210.3390/d15040572Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient IntakeMaria Bashenkhaeva0Yelena Yeletskaya1Irina Tomberg2Artyom Marchenkov3Lubov Titova4Yuri Galachyants5Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya Str., 3, 664033 Irkutsk, RussiaLimnological Institute, Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya Str., 3, 664033 Irkutsk, RussiaLimnological Institute, Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya Str., 3, 664033 Irkutsk, RussiaLimnological Institute, Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya Str., 3, 664033 Irkutsk, RussiaLimnological Institute, Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya Str., 3, 664033 Irkutsk, RussiaLimnological Institute, Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya Str., 3, 664033 Irkutsk, RussiaIn an aquatic ecosystem, the supply of nutrients is essential for the biogeochemical cycle, and it affects the taxonomic composition of the microbial communities. Here, by using high-throughput sequencing (HTS) of the 16S and 18S rRNA gene fragments, we compared free-living (FL) and particle-associated (PA) bacterial communities and microeukaryotic communities in the areas with different nutrient intakes in freshwater Lake Baikal during the ice-covered and summer periods. Samples were taken at the inflow of the Selenga River, which is the main tributary of the lake, and at several established coastal research stations. The metabolic potential of the bacterial communities was predicted using PICRUSt. Differences were found in both FL and PA communities of the river mouth compared to the photic zone of the lake. The composition of FL communities was significantly different between the sampling sites in the ice-covered period, which is most likely influenced by different hydrochemical conditions. In contrast, the PA communities were more similar during the ice-covered period, but they changed considerably from spring to summer and their diversity increased. The diversity of the microeukaryotic communities also increased in summer, which may have contributed to the increase in bacterial diversity. In co-occurrence networks analysis, the number of interconnected bacterial OTUs in FL exceeded those for PA. The FL communities were dominated by <i>Actinobacteriota</i>, while the major PA OTUs belonged to a mixed cluster, which were mainly assigned to the phyla <i>Bacteroidota</i> and <i>Verrucomicrobiota</i>. As a result, PA communities were enriched in pathways responsible for the metabolism of sulfur, fucose, cellulose and urea. Our results confirm the difference between the FL and PA bacterial communities in Lake Baikal. These results also highlight the complex pattern of interactions between bacteria and microeukaryotes in a natural freshwater ecosystem across spatial and temporal scales.https://www.mdpi.com/1424-2818/15/4/572free-livingparticle-associatedbacteriamicroeukaryotesfreshwaterhigh-throughput sequencing
spellingShingle Maria Bashenkhaeva
Yelena Yeletskaya
Irina Tomberg
Artyom Marchenkov
Lubov Titova
Yuri Galachyants
Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient Intake
Diversity
free-living
particle-associated
bacteria
microeukaryotes
freshwater
high-throughput sequencing
title Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient Intake
title_full Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient Intake
title_fullStr Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient Intake
title_full_unstemmed Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient Intake
title_short Free-Living and Particle-Associated Microbial Communities of Lake Baikal Differ by Season and Nutrient Intake
title_sort free living and particle associated microbial communities of lake baikal differ by season and nutrient intake
topic free-living
particle-associated
bacteria
microeukaryotes
freshwater
high-throughput sequencing
url https://www.mdpi.com/1424-2818/15/4/572
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