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Lake Hévíz is a unique thermal spa located in Hungary. Owing to the thermal springs nourishing the lake, it has a relatively rapid water turnover. In spring 2011 a comprehensive embankment reconstruction was performed to preserve the water supply of the surrounding wetland habitats. The physical and chemical parameters as well as the planktonic microbial communities were studied with special respect to the effect of the disturbance of the water of Lake Hévíz. According to the abiotic components, both temporal and spatial differences were revealed with the exception of autumn samples. The reconstruction resulted in a short term but dramatic alteration of the total planktonic bacterial and cyanobacterial community structures as revealed by denaturing gradient gel electrophoresis. In addition, greater seasonal than spatial differences of bacterial communities were also observed. Planktonic bacterial community composition of Lake Hévíz included mainly typical freshwater species within phylum Actinobacteria, Chloroflexi, Cyanobacteria and class Alpha-, Beta- and Gamma-proteobacteria. Most of them were aerobic or facultative anaerobic heterotrophic but chemolitotrophic (e.g. Thiobacillus) or photolithotrophic (e.g. Cyanobacteria and Chloroflexi) autotrophic microbes were also identified.

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In this study, changes in the bacterial community composition of the well waters of Harkány Spa were examined. Physical and chemical properties of mixing subsurface cold and thermal karst waters were correlated to shifts in bacterial community structures analyzed by denaturing gradient gel electrophoresis (DGGE) and principal component analysis (PCA). In addition, mineral components of the pellets were investigated by scanning electron microscopy. Samples from the effluent waters of Büdöstapolca I and II, Matty and Thermal VI wells were taken seasonally in 2007 and 2008. The comparison of the results of DGGE and PCA analyses showed that bacterial communities from the Büdöstapolca wells were distinct from those of Matty and Thermal VI, but seasonal changes were not detected. According to the phylogenetic analysis of the excised DGGE bands, presence of chemolithotrophic Proteobacteria (Thiobacillus, Thiothrix, and distant relatives of Sulfurospirillum) were typical in the Büdöstapolca wells, while members of Actinobacteria (Plantibacter, Actinobacterium, Microbacterium) and Firmicutes (Planococcus) were characteristic to the Matty and Thermal VI wells. In the pellets pyrite framboid crystals were observed by electron microscopy, which are minerals known to be biologically induced by dissimilatory iron- and sulfur (sulfate)-reducing bacteria.

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Bacterial communities from the sulfide containing curative well waters of Harkány Spa (Hungary) were investigated by cultivation independent molecular cloning and Denaturing Gradient Gel Electrophoresis (DGGE) methods between 2006 and 2008. The DGGE profiles of the bacterial communities originated from the wells of lukewarm waters showed seasonal similarities and were highly different from the thermal well. From the four clone libraries 22 different eubacterial species or genera were identified by sequence analysis. The majority of the clones of the lukewarm waters belonged to unidentified Epsilon-proteobacteria, Desulfocapsa sp. and Thiothrix spp., while the dominant clones of the thermal water were affiliated with the genus Denitratisoma sp. Most of the identified species and genera were related to bacteria with obligate or facultative chemolithotrophic sulfur metabolism, so the microbes of the curative waters may participate in the sulfur-cycle of the wells.

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Acta Microbiologica et Immunologica Hungarica
Authors: Andrea Németh, Barbara Szirányi, Gergely Krett, Endre Janurik, Tünde Kosáros, Ferenc Pekár, Károly Márialigeti, and Andrea Borsodi

Geothermal wells characterized by thermal waters warmer than 30°C can be found in more than 65% of the area of Hungary. The examined thermal wells located nearby Szarvas are used for heating industrial and agricultural facilities because of their relatively high hydrocarbon content. The aim of this study was to reveal the prokaryotic community structure of the water of SZR18, K87 and SZR21 geothermal wells using molecular cloning methods and Denaturing Gradient Gel Electrophoresis (DGGE). Water samples from the outflow pipes were collected in 2012 and 2013. The phylogenetic distribution of archaeal molecular clones was very similar in each sample, the most abundant groups belonged to the genera Methanosaeta, Methanothermobacter and Thermofilum. In contrast, the distribution of bacterial molecular clones was very diverse. Many of them showed the closest sequence similarities to uncultured clone sequences from similar thermal environments. From the water of the SZR18 well, phylotypes closely related to genera Fictibacillus and Alicyclobacillus (Firmicutes) were only revealed, while the bacterial diversity of the K87 well water was much higher. Here, the members of the phyla Thermodesulfobacteria, Proteobacteria, Nitrospira, Chlorobi, OP1 and OPB7 were also detected besides Firmicutes.

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A talajok hazai és nemzetközi kutatásában egyre nagyobb szerepet kap a talajok mikrobiótájának vizsgálata. Hazai viszonylatban szikes talajokon eddig kevés ilyen irányú kutatás történt. Kutatásunkban kiskunsági szikes talajok mikrobaközösségeinek katabolikus aktivitás mintázatát vizsgáltuk Apajpusztáról származó mintákon. A mintavételhez négy, a szikesedés különböző fázisaira jellemző növényzettel rendelkező területet választottunk ki (szoloncsák vaksziknövényzet, kiskunsági szikfoknövényzet, ürmös szikespuszta és füves szikespuszta), ezek területéről a talaj mikrobiológiai szempontból legaktívabbnak tekintett 0-10 cm-es rétegét mintáztuk.

A minták néhány fontosabb talajtani paraméterét meghatároztuk (szemcseösszetétel, pH, só-, humusz- és mésztartalom, valamint néhány fontosabb tápelem mennyisége). A négy eltérő növényzetű terület között a talajtani paramétereik alapján is jelentős különbségeket tapasztaltunk.

A minták mikrobiológiai aktivitását az itthon még kevéssé ismert mikrorespirációs (MicroRespTM) módszerrel vizsgáltuk. Ennek során a talajmintákhoz 23 különböző szerves szubsztrátot adtunk, és az általuk indukált légzési válaszon keresztül mértük, hogy az egyes talajminták mikrobaközösségei milyen mértékben képesek hasznosítani az egyes szubsztrátokat. Az így kapott, közösségre jellemző katabolikus aktivitás mintázatokat főkomponens elemzéssel és kanonikus korreszpondancia elemzéssel értékeltük.

Eredményeink alapján a mikrorespirációs módszer egyértelműen alkalmas az általunk vizsgált talajok mikrobiótájának elkülönítésére. Az egyes minták katabolikus aktivitás mintázatai közötti különbségek egybevágtak a minták közötti, talajfizikai és —kémiai tulajdonságban megfigyelt eltérésekkel.

A kutatást az OTKA (K 108572) támogatta.

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Lake Hévíz is the largest natural warm water lake of Europe. The curative mud of the lake comprises volcanic and marsh components although their species composition is hardly known yet. The aim of the present study was to gain information about the distribution and species diversity of bacterial communities inhabiting the sediment of Lake Hévíz using cultivation-based and molecular cloning methods. Samples from two depths and locations were taken in 2004 and 2007. Representatives of the altogether 255 bacterial isolates were affiliated with the phyla Firmicutes, Actinobacteria, Proteobacteria and Bacteroidetes. The most abundant groups belonged to the genus Bacillus (Firmicutes). Many of Lake Hévíz isolates showed the highest sequence similarity to bacteria known to be plant associated or members of normal human microbiota as well as participating in decomposition of highly resistant organic materials. In the three clone libraries, phylotypes belonging to altogether different phyla (Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes, Cyanobacteria, Chlorobi, Chloroflexi, Deferribacteres, Nitrospirae, Spirochaetes and Verrucomicrobia) were revealed from which members of Gammaproteobacteria and Cyanobacteria proved to be the most abundant. Regardless of the sampling times and methodology used, high spatial heterogeneities of bacterial community structures were characteristic of the sediment of Lake Hévíz.

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A preliminary study was conducted to compare the community level physiological profile (CLPP) and genetic diversity of rhizosphere microbial communities of four plant species growing nearby Kiskunság soda ponds, namely Böddi-szék, Kelemen-szék and Zab-szék. CLPP was assessed by MicroResp method using 15 different substrates while Denaturing Gradient Gel Electrophoresis (DGGE) was used to analyse genetic diversity of bacterial communities. The soil physical and chemical properties were quite different at the three sampling sites. Multivariate statistics (PCA and UPGMA) revealed that Zab-szék samples could be separated according to their genetic profile from the two others which might be attributed to the geographical location and perhaps the differences in soil physical properties. Böddi-szék samples could be separated from the two others considering the metabolic activity which could be explained by their high salt and low humus contents. The number of bands in DGGE gels was related to the metabolic activity, and positively correlated with soil humus content, but negatively with soil salt content. The main finding was that geographical location, soil physical and chemical properties and the type of vegetation were all important factors influencing the metabolic activity and genetic diversity of rhizosphere microbial communities.

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Agrokémia és Talajtan
Authors: Tibor Szili-Kovács, Ágnes Bárány, Anna Füzy, Tünde Takács, Gergely Krett, Ramóna Kovács, and Andrea Borsodi

A szikes talajok szélsőséges vízháztartásuk, nagy sótartalmuk és alkalikus kémhatásuk miatt az élőlények alkalmazkodását alaposan próbára teszik. A talaj mikrobiális közösség katabolikus aktivitás mintázatát hasonlítottuk össze három szikes tó, a Böddi-szék, a Kelemen-szék és a Zab-szék (Felső-Kiskunsági szikes tavak) partközeli vegetációjának rizoszférájában az iszaptól a zsiókáson és a mézpázsiton keresztül a homoki legelőig. Feltételeztük, hogy a szikes jellegben és a növényzetben meglévő különbségek a mikrobiális közösségre is hatást gyakorolnak. Kezdeti eredményeink azt mutatták, hogy a szubsztrát hasznosítási mintázat alapján az egyes minták jól elkülönültek egymástól. Az alaprespiráció elsősorban a talaj humusztartalmával mutatott szoros összefüggést. A katabolikus aktivitás mintázatokat 5 szubsztrát alapján a gázkromatográfiás SIR méréssel a pH és EC, míg 15 szubsztrát alapján mikrorespirációval a pH és humusztartalom szignifikánsan befolyásolta, a növényzet közvetlen hatása kevésbé volt igazolható.

A szélsőséges talajtulajdonságokkal jellemezhető élőhelyeken, mint amilyenek a szikesek, a növények túlélésében az arbuszkuláris mikorhiza (AM) gombák fontos szerepet játszanak. Az AM gombák kolonizációjában jelentős különbség adódott két domináns növényfaj, a sziki őszirózsa és a sziki mézpázsit között, az előbbi jóval erőteljesebb kolonizációt mutatott. Ugyanazon növényfaj AM kolonizációja a három területen eltérő volt, ami nem magyarázható a talaj tulajdonságokkal.

A kutatást az OTKA (K 108572) támogatta.

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Disposal of used geothermal waters in Hungary often means temporary storage in reservoir lakes to reduce temperature and improve water quality. In this study, the physical and chemical properties and changes in the bacterial community structure of a reservoir lake system in southeast region of Hungary were monitored and compared through 2 years, respectively. The values of biological oxygen demand, concentrations of ammonium ion, total inorganic nitrogen, total phosphorous, and total phenol decreased, whereas oxygen saturation, total organic nitrogen, pH, and conductivity increased during the storage period. Bacterial community structure of water and sediment samples was compared by denaturing gradient gel electrophoresis (DGGE) following the amplification of the 16S rRNA gene. According to the DGGE patterns, greater seasonal than spatial differences of bacterial communities were revealed in both water and sediment of the lakes. Representatives of the genera Arthrospira and Anabaenopsis (cyanobacteria) were identified as permanent and dominant members of the bacterial communities.

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