Culturable diversity of aerobic halophilic archaea (Fam. Halobacteriaceae) from hypersaline, meromictic Transylvanian lakes
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Perennially stratified salt lakes situated in the Transylvanian Basin (Central Romania) were surveyed for the diversity of culturable halophilic archaea (Fam. Halobacteriaceae). The physical and chemical characteristics of the waters indicated that all the investigated lakes were meromictic and neutral hypersaline. Samples collected from upper, intermediate, and deeper water layers and sediments were used for the isolation of halophilic strains followed by 16S rRNA gene-based identification and phenotypic characterization. The phylogenetic analysis of the 16S rRNA gene sequences revealed that all 191 isolates reported in this study and 43 strains previously isolated were affiliated with the family Halobacteriaceae and classified to 18 genera. Haloferax was the most frequently isolated genus (~47 %), followed by Halobacterium spp. (~12 %), and Halorubrum spp. (~11 %). Highest culturable diversity was detected in Brâncoveanu Lake, the oldest and saltiest of all studied lakes, while the opposite was observed in the most stable and least human-impacted Fără Fund Lake. One strain from Ursu Lake might possibly constitute a novel Halorubrum species as shown by phylogenetic analysis. Several haloarchaeal taxa recently described in Asian (i.e., Iran, China) saline systems were also identified as inhabiting the Transylvanian salt lakes thus expanding our knowledege on the geographic distribution of Halobacteriaceae.
KeywordsCulturable haloarchaea Genus-level diversity Haloferax spp. Meromictic lake Site-specific diversity
This work was supported by a Grant of the Romanian National Authority for Scientific Research, CNCS–UEFIS-CDI, project number PN-II-ID-PCE-2011-3-0546. Andreea Baricz was partially funded by a grant from the Romanian Ministry of National Education, project PN 09-360201. Adrian-Ştefan Andrei was supported by a PhD scholarship financed by POSDRU/159/1.5/S/132400. Gabriela Teodosiu was funded by project no. RO1567-IBB05/2014 from the Institute of Biology Bucharest of Romanian Academy. We are grateful to Daniela Buta (Ocna Sibiului), Dr. Ovidiu Mera (Turda), and Nagy Fülop János (Sovata) for the permission to enter the study areas.
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