Introduction

1. Introduction In Hungary, thermal waters utilized in energy producing processes are usually released to natural surface waters after being incubated in reservoirs. The Barex Ltd. whichis located in Szarvas (South-Eastern Hungary) utilizes the geothermic energy of three thermal wells for heating. According to the chemical analysis of the water samples, the utilized thermal water is anaerobic, alkaline, rich in phenol derivatives and is of high salinity. Since many of these parameters reach the threshold allowed in natural waters, it cannot be directly releasedinto natural water bodies, therefore it is storedin artificial lakes for a time. The subject of this investigation was the Barex Reservoir System which consists of 4 separate but interconnected artificial water bodies. In this study we examined the first and the second lake of this system (Figs. 1and 2). Since little is known about the prokaryotic inhabitants of these types of environments, the aim of this study was to gain insight to the structure and composition of the microbial communities. • Materials and Methods • Exploration of the phylogenetic diversity was carried out by the construction of4 archaealand4 bacterial clone libraries. • (Sampling: September 2012) • BT1_W – water sample from the first lake • BT2_W – water sample from the second lake • BT1_S – sediment sample from the first lake • BT1_B – biofilm sample from reed stem surface • Community DNA extraction (Mo-Bio Ultra Clean Soil DNAIsolation Kit) • 16S rDNA amplification with primers; Bacteria: 27F-1401R, Archaea: A109F and A958R. • Clone library construction(pGEM®-23T Vector System, Promega, USA). • Grouping of molecular clones by ARDRA using BsuRIand Hin6I enzymes • Sequence analysis of representative clones • Alignment of sequences by EzTaxon-e and NCBI-BLAST Prokaryotic phylogenetic diversity scanning of saline geothermal water utilized for energetic purposes studied by clone librariesSzirányi B.*1, Szalay A.1, Krett G.1, Janurik E.2, Pekár F.2, Márialigeti K.1, Borsodi A.K.11Department of Microbiology, Eötvös Loránd University, Pázmány P. sétány 1/C, H-1117 Budapest, Hungary2Research Institute for Fisheries, Aquaculture and Irrigation, Szarvas, Hungary*kuszogeb@gmail.com Fig. 2. The first lake of the Barex Reservoir System Fig. 1. Satellite image of theBarexReservoir System • Results and Discussion • Archaeal communities (Fig. 3): only the phylum Euryarcheota was represented. • 19.3% of the archaeal clones showed the highest sequence similarity to uncultured environmental clones. • Bacterial communities (Fig. 4): members of 9 different phyla were represented. • Biofilm and sediment samples (Fig. 4) were more diverse than the water samples according to both archaeal and bacterial clone libraries. • Bacterial libraries (Figs. 5-8): phylotypes of 27/15/6/12 different orders were present in the S/B/W1/W2 samples; only members of Burkholderiales were detected in all samples. • Water samples (mainly W1) were dominated by members of phylum Cyanobacteria. • The majority of molecular clones were closely related to haloalkaliphilic bacteria capable of utilizing a wide range of carbon compounds. • Several phylotypes belonging to the genus Azoarcus, which is known to be capable of the biodegradation of aromatic hydrocarbons, were found in sediment samples. Fig. 4. Phylogenetic affiliation of all four bacterial clone libraries on the phylum level (except for the classes of Proteobacteria).Total number of clones per a clone library was referred to as 100%. Fig. 6. Percentile distribution of the clones in the BT1_B clone library Fig. 5. Percentile distribution of the clones in the BT1_S clone library Fig. 6. Percentagedistributionof molecularclonesintheBT1_S clone library Fig. 3. Bootstrap consensus phylogenetic tree of the archaealmolecularclones (BT1W, BT2W, BT1B, BT1S libraries) constructed with ML method. The number of the clones in the same ARDRA groups of the sample is given in parentheses following the signs of the clones. Fig. 8. Percentile distribution of the clones in the BT2_W clone library Fig. 7. Percentile distribution of the clones in the BT1_W clone library