Author(s)

Anastasia Touka¹, Katerina Vareli^1,2, Maria Igglezou¹, Nikolaos Monokrousos², Dimitrios Alivertis², John M. Halley², Sotiris Hadjikakou³, Stathis Frillingos⁴, Ioannis Sainis^1,2*

¹Interscience Molecular Oncology Laboratory (iMol), Cancer Biobank Center (UICBC), University of Ioannina, Ioannina, Greece.
²Department of Biological Applications and Technology, School of Health Sciences, University of Ioannina, Ioannina, Greece.
³Department of Chemistry, Section of Inorganic and Analytical Chemistry, University of Ioannina, Ioannina, Greece.
⁴Department of Medicine, School of Health Sciences, Laboratory of Biological Chemistry, University of Ioannina, Ioannina, Greece.

Ancient European lakes are clustered within a radius of 300 km around Lake Ohrid. Information concerning microbial diversity in these lakes is limited. We studied diversity of the dominant prokaryotic phylotypes in the sediments in one of these lakes, known as Lake Pamvotis. The analysis was performed in samples from two stations for four seasons of the same year. DNA extraction followed by PCR amplification (16S rDNA), Denaturing Gradient Gel Electrophoresis, cloning and sequencing was applied in order to reveal the sequence signatures of the dominant bacterial and archaeal phylotypes. Bacterial and archaeal cell numbers were quantified by real-time PCR. Several environmental variables measured in parallel, including pH, Nickel, Chromium, Arsenic, Calcium, Total Nitrogen and Total Carbon, were found to affect strongly the prokaryotic abundances. Most of the identified sequences of Bacteria belong to Proteobacteria and most of the sequences of Archaea belong to Euryarchaeota. The great majority of these bacterial (84.21%) and archaeal sequences (95.65%) have no cultivated counterparts in the databases. In addition, many of these bacterial (50.88%) and archaeal sequences (20.65%) correspond to potentially new species. Six of the bacterial sequences constitute a new class of Cyanobacteria which we have named “Lake Pamvotis cluster” (LPC). Our findings highlight Lake Pamvotis as a habitat for several previously unidentified species of Bacteria and Archaea.

Ancient Lakes, Lake Pamvotis, Bacteria, Archaea

Touka, A. , Vareli, K. , Igglezou, M. , Monokrousos, N. , Alivertis, D. , Halley, J. , Hadjikakou, S. , Frillingos, S. and Sainis, I. (2018) Ancient European Lakes: Reservoirs of Hidden Microbial Diversity? The Case of Lake Pamvotis (NW Greece). Open Journal of Ecology, 8, 537-578. doi: 10.4236/oje.2018.810033.