engleski

Rogoznica Lake – an Extreme Seawater Environment Hosting Specific Sulfate-reducing Bacterial Community

Rogoznica Lake is seasonally stratified and highly eutrophic seawater lake with hypoxic/anoxic layer usually occurring below the depth of 8 m. Due to high phytoplankton activity upper part of the water column is well oxygenated while remineralization processes enhance deposition of organic matter and nutrients in deeper layer where appearance of hypoxia/anoxia and microbially production of H2S is confirmed. We investigated distribution, diversity and abundance of sulfate- reducing bacteria (SRB) during stratified summer and winter season, by targeting six major phylogenetic groups of SRB using specific 16S rRNA primer sets. Our results implied existence of distinct SRB populations in the water column and sediment. Rarefraction analysis revealed higher diversity of the SRB occupying water layer then the one found in sediments, independent of the sampling season. However, seasonal variations in diversity were observed in the water column and sediment. SRB community was more diverse in winter compared to summer season in water layer while, in opposite, sediment community evolved during summer was more diverse then the one found in winter. Water layer community seems to be more susceptible to changes of physico-chemical parameters, while those in sediment do not follow the same pattern having prorogated response to the changes in the Lake. Low homology of our sequences (as low as 85%) to the sequences in NCBI database further indicated that Rogoznica Lake harbor habitat- specific SRB populations that cannot be associated to known SRB but rather to uncultured bacteria found in extreme marine environments.

extreme marine environments ; Rogoznica Lake ; sulfate-reducing bacteria

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