Unusually High Archaeal Diversity in a Crystallizer Pond, Pomorie Salterns, Bulgaria, Revealed by Phylogenetic Analysis

Abstract

Recent studies on archaeal diversity in few salterns have revealed heterogeneity between sites and unique structures of separate places that hinder drawing of generalized conclusions. Investigations on the archaeal community composition in P18, the biggest crystallizer pond in Pomorie salterns (PS) (34% salinity), demonstrated unusually high number of presented taxa in hypersaline environment. Archaeal clones were grouped in 26 different operational taxonomic units (OTUs) assigned to 15 different genera from two orders, Halobacteriales and Haloferacales. All retrieved sequences were related to culturable halophiles or unculturable clones from saline (mostly hypersaline) niches. New sequences represented 53.9% of archaeal OTUs. Some of them formed separate branches with 90% similarity to the closest neighbor. Present results significantly differed from the previous investigations in regard to the number of presented genera, the domination of some genera not reported before in such extreme niche, and the identification of previously undiscovered 16S rRNA sequences.

Microbial Communities From the World's Largest Lithium Reserve, Salar de Atacama, Chile: Life at High LiCl Concentrations

“…An extensive literature exists describing the presence of various taxa living in extremely saline conditions (e.g., Brisou et al, ; Imhoff et al, ; Pedrós‐Alió, ; Trüper & Galinski, ; Ventosa et al, ); however, salinity in these studies typically reflects sodium salts. NaCl‐dominated salterns have been reported to be dominated by Euryarchaeota (Kambourova et al, ; Maturrano et al, ) and Gammaproteobacteria (Maturrano et al, ; Yeon et al, ), and to show high archaeal diversity (Andrei et al, ; Kambourova et al, ), similar to our results, where Euryarchaeota dominate the natural brine. Nevertheless, this does not occur in brines with other chemical compositions.…”

Phylogenetic analysis of the bacterial community in a crystallizer pond, Pomorie salterns, Bulgaria

“…Although the share of new sequences in the bacterial library (42.3%) was less than that in the archaeal one (53.9%) [10], the degree of novelty concerning the higher taxonomic level and sequences with similarity of less than 90% to the closest match and 85% to the culturable neighbour were established. Bacterial diversity on the level of higher taxa could be explained by the reported observation that halophilic bacteria are less mobile or less robust across large distances than halophilic archaea and show a higher tendency towards endemism [36].…”

“…The similarity between them was 81%, which was far from the 15% sequence divergence cut-off for a new phylum. The big fraction of novel bacterial and archaeal [10] sequences suggests presence of novel taxa at different levels in the investigated environment. Candidate division SR1, which has been previously included as a part of Candidate division OP11 [40], could be a heterogeneous group and further investigations suppose a division of this phylum.…”

“…It was significantly higher than that observed by other authors in hypersaline salterns with higher than 30% salt content of the sampling site (Table 2): three bacterial genera have been established in Maras salterns, Peru [21]; five bacteral genera in a 32% salt pond, Santa Pola salterns, Spain [19]; four bacterial genera in 30% salt ponds, Guerrero Negro saltern, Mexico [22]; and five bacterial genera in the 31% salt pond S5 from a solar saltern in Tunisia [23]. The equal number of genera (15 each) represented in both archaeal [10] and bacterial communities from PS differs from the observations of other authors that members of the domain Archaea are dominant, whereas those of the domain Bacteria are slightly represented in hypersaline environments [4,[21][22][23][24]. Like our study, Dillon et al [22] have reported similar archaeal and bacterial 16S rRNA diversity (four genera each) in a hypersaline pond in evaporative Guerrero Negro salterns.…”

“…Recently, we reported on the archaeal diversity in Pomorie salterns [10] and here we describe the results from our investigation on the structure of the other microbial domain of life, Bacteria. Pomorie salterns (42.63N, 27.62E) is located north of the town of Pomorie, at the Bulgarian Black Sea coast.…”