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Aquatic Microbial Ecology

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AME 84:141-154 (2020)  -  DOI:

Impact of euxinic holomictic conditions on prokaryotic assemblages in a marine meromictic lake

Milan Čanković1,*, Jurica Žučko2, Ines Petrić1, Marija Marguš1, Irena Ciglenečki1

1Division for Marine and Environmental Research, Rudér Bošković Institute, Bijenićka cesta 54, 10000 Zagreb, Croatia
2Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
*Corresponding author:

ABSTRACT: The water column of marine Rogoznica Lake (Croatia) is stratified throughout the year. However, on rare occasions, the lake exhibits complete mixing, primarily driven by meteorological conditions. On such occasions, anoxic, sulfide-rich bottom water mixes with the oxic surface layer, triggering both the oxidation of sulfide predominantly to colloidal sulfur and the establishment of euxinic conditions throughout the water column. We investigated prokaryotic communities during euxinic holomictic conditions. High-throughput sequencing of the 16S rRNA gene showed that these sulfur-driven communities were dominated by Planctomycetales, chemolithotrophic Epsilonbactereota (mainly Arcobacteraceae) and Gammaproteobacteria (Thioglobaceae), followed by Alpha- (Rhodobacteraceae) and Deltaproteobacteria (Desulfobulbaceae and Desulfobacteraceae). The majority of archaeal sequences belonged to Nanoarchaeota, all of which were designated as Woesearchaeia. This class has not been recorded in other meromictic lakes. Both bacterial and archaeal 16S rRNA gene abundance did not vary significantly across the vertical profile of the lake, as shown by quantitative PCR. However, hierarchical clustering showed a significant difference between the microbial assemblage structure in stratified periods and during a holomictic event. Besides the structure, this stressful event had a manifold effect on bacterial and archaeal assemblages by decreasing their diversity and abundance when compared to the usual stratified conditions.

KEY WORDS: Euxinia · Meromictic lake · Rogoznica Lake · Microbial community · 16S amplicon sequencing · Environmental stress

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Cite this article as: Čanković M, Žučko J, Petrić I, Marguš M, Ciglenečki I (2020) Impact of euxinic holomictic conditions on prokaryotic assemblages in a marine meromictic lake. Aquat Microb Ecol 84:141-154.

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