TITLE:
Ancient European Lakes: Reservoirs of Hidden Microbial Diversity? The Case of Lake Pamvotis (NW Greece)
AUTHORS:
Anastasia Touka, Katerina Vareli, Maria Igglezou, Nikolaos Monokrousos, Dimitrios Alivertis, John M. Halley, Sotiris Hadjikakou, Stathis Frillingos, Ioannis Sainis
KEYWORDS:
Ancient Lakes, Lake Pamvotis, Bacteria, Archaea
JOURNAL NAME:
Open Journal of Ecology,
Vol.8 No.10,
October
31,
2018
ABSTRACT: 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.