Deinococcus fonticola sp. nov., isolated from a radioactive thermal spring in Hungary.

A Gram-stain-negative, aerobic, non-motile and coccus-shaped bacterium, designated strain FeSDHB5-19T, was isolated from a biofilm sample collected from a radioactive thermal spring (Budapest, Hungary), after exposure to 5 kGy gamma radiation. A polyphasic approach was used to study the taxonomic properties of strain FeSDHB5-19T, which had highest 16S rRNA gene sequence similarity to Deinococcus antarcticus G3-6-20T (96.5 %). The 16S rRNA gene sequence similarity to type strains of other Deinococcus species were 93.0 % or lower. The DNA G+C content of the draft genome sequence, consisting of 3.9 Mb, was 63.9 mol%. Strain FeSHDB5-19T was found to grow at temperatures of 10-32 °C (optimum, 28 °C) and pH 5-10 (pH 6.5-7.5) and tolerated up to 1.5 % NaCl (w/v) with optimum growth at 0-0.5 % NaCl. The predominant fatty acids (>10 %) were C16 : 0 and C16 : 1ω7c. The cell-wall peptidoglycan type was A3ß l-Orn-Gly1-2. The whole-cell sugars were glucose and low amounts of galactose. Strain FeSDHB5-19T possessed MK-8 as the predominant respiratory quinone, typical of the genus Deinococcus. The polar lipid profile contained unidentified phosphoglycolipids and unidentified glycolipids. The isolate was found to be highly resistant to gamma (D10<8 kGy) and UV (D10~800 J m-2) radiation. According to its genotypic, phenotypic and chemotaxonomic characteristics, strain FeSDHB5-19T represents a novel species in the genus Deinococcus, for which the name Deinococcusfonticola sp. nov. is proposed. The type strain is FeSDHB5-19T (=NCAIM B.02639T=DSM 106917T).

Anaerobacillus alkaliphilus sp. nov., a novel alkaliphilic and moderately halophilic bacterium.

Two alkaliphilic and moderately halophilic bacterial strains B16-10T and Z23-18 characterized by optimal growth at pH 9.0-10.0 and 5 % (w/v) NaCl, were isolated from the rhizosphere soil of the bayonet grass (Bolboschoenus maritimus) in the Kiskunság National Park, Hungary. Cells of both strains stained Gram-positive, were motile straight rods, and formed terminal, ellipsoidal endospores with swollen sporangia. The isolates were facultative anaerobic, catalase positive, oxidase negative. Both strains contained meso-diaminopimelic acid as diagnostic diaminoacid of the peptidoglycan. Menaquinone-7 (MK-7) was the predominant isoprenoid quinone. Anteiso-C15 : 0, C16 : 1ω11c and iso-C14 : 0 were the major cellular fatty acids. The DNA G+C content of both strains was 35.8 mol%. The 16S rRNA gene based phylogenetic analysis revealed that the facultative anaerobic strains B16-10T and Z23-18 showed the highest similarities to the type strains of anaerobic Anaerobacillus isosaccharinicus NB2006T (98.7 and 99.1 %), A. macyae JMM-4T (98.2 and 98.4 %), A. alkalidiazotrophicus MS 6T (97.7 and 98.4 %), A. alkalilacustris Z-0521T (97.5 and 98.3 %) and A. arseniciselenatis DSM 15340T (97.5 and 98.2 %). However, the distinctive phenotypic and genetic results of this study confirmed that strains B16-10T and Z23-18 represent a novel species, for which the name Anaerobacillus alkaliphilus sp. nov. is proposed. The type strain is B16-10T (=DSM 29790T=NCAIM B 02608T).

Dual bloom of green algae and purple bacteria in an extremely shallow soda pan.

In April 2014, dual bloom of green algae and purple bacteria occurred in a shallow, alkaline soda pan (Kiskunság National Park, Hungary). The water was only 5 cm deep, in which an upper green layer was clearly separated from a near-sediment purple one. Based on microscopy and DNA-based identification, the upper was inhabited by a dense population of the planktonic green alga, Oocystis submarina Lagerheim, while the deeper layer was formed by purple, bacteriochlorophyll-containing bacteria, predominated by Thiorhodospira and Rhodobaca. Additional bacterial taxa with a presumed capability of anoxygenic phototrophic growth belonged to the genera Loktanella and Porphyrobacter. Comparing the bacterial community of the purple layer with a former blooming event in a nearby soda pan, similar functional but different taxonomic composition was revealed. Members from many dominant bacterial groups were successfully cultivated including potentially new species, which could be the result of the application of newly designed media.

Biofilm forming bacteria and archaea in thermal karst springs of Gellért Hill discharge area (Hungary).

The Buda Thermal Karst System (BTKS) is an extensive active hypogenic cave system located beneath the residential area of the Hungarian capital. At the river Danube, several thermal springs discharge forming spring caves. To reveal and compare the morphological structure and prokaryotic diversity of reddish-brown biofilms developed on the carbonate rock surfaces of the springs, scanning electron microscopy (SEM), and molecular cloning were applied. Microbial networks formed by filamentous bacteria and other cells with mineral crystals embedded in extracellular polymeric substances were observed in the SEM images. Biofilms were dominated by prokaryotes belonging to phyla Proteobacteria, Chloroflexi and Nitrospirae (Bacteria) and Thaumarchaeota (Archaea) but their abundance showed differences according to the type of the host rock, geographic distance, and different water exchange. In addition, representatives of phyla Acidobacteria, Actinobacteria, Caldithrix, Cyanobacteria, Firmicutes Gemmatimonadetes, and several candidate divisions of Bacteria as well as Crenarchaeota and Euryarchaeota were detected in sample-dependent higher abundance. The results indicate that thermophilic, anaerobic sulfur-, sulfate-, nitrate-, and iron(III)-reducing chemoorganotrophic as well as sulfur-, ammonia-, and nitrite-oxidizing chemolithotrophic prokaryotes can interact in the studied biofilms adapted to the unique and extreme circumstances (e.g., aphotic and nearly anoxic conditions, oligotrophy, and radionuclide accumulation) in the thermal karst springs.

The effect of reconstruction works on planktonic bacterial diversity of a unique thermal lake revealed by cultivation, molecular cloning and next generation sequencing.

The aim of this study was to gain detailed information about the diversity of planktonic bacterial communities of a worldwide special peat bedded natural thermal spa lake, and to reveal the effect of a lake wall reconstruction work. To compare the efficiency of different methods used for analyzing bacterial diversity, cultivation, molecular cloning and pyrosequencing were applied simultaneously. Despite the almost unchanged physical-chemical parameters and cell count values of lake water, remarkable differences were observed in the planktonic bacterial community structures during and after the reconstruction by all applied microbiological approaches. Rhodobacter sp. was found to be one of the most abundant community members during the works probably due to the sediment stirring effect of the reconstruction. Following the reconstruction higher diversity was detected than during the works by all approaches. Bacterial strains related to species Chryseobacterium and Exiguobacterium, furthermore sequences related to Arcobacter, Gemmobacter and MWH-UniP1 aquatic group were identified in the highest proportion at that time. Although the differences revealed by cultivation based and independent community structures were significant, only minor disparities were found by molecular cloning and next generation sequencing techniques.

Nesterenkonia pannonica sp. nov., a novel alkaliphilic and moderately halophilic actinobacterium.

An alkaliphilic and moderately halophilic bacterial strain characterized by optimal growth at pH 9.0-10.0 and with 5-7 % (w/v) NaCl, designated BV-35T, was isolated from water of a soda pan located in Kiskunság National Park, Hungary. Cells of the orange-pigmented colony were Gram-stain-positive, non-motile and non-endospore-forming coccoid rods. The isolate was strictly aerobic, catalase-positive and oxidase-negative. Strain BV-35T displayed a peptidoglycan similar to type A4α, l-Lys-l-Glu (A11.54 according to www.peptidoglycan-types.info) but containing additionally 4-aminobutyric acid. Menaquinone-7 (MK-7) was the predominant isoprenoid quinone, and anteiso-C15 : 0 and anteiso-C17 : 0 were its major cellular fatty acids. The DNA G+C content of strain BV-35T was 65.4 mol%. Based on 16S rRNA gene sequence similarities, the novel isolate showed the closest relationship to Nesterenkonia populi GP 10-3T (97.9 %). The DNA-DNA relatedness between BV-35T and N. populi was 46.7 %. The distinguishing phenotypic and genetic results of this polyphasic study revealed that strain BV-35T represents a novel member of the genus Nesterenkonia, for which the name Nesterenkonia pannonica sp. nov. is proposed. The type strain is BV-35T (=DSM 29786T=NCAIM B 02606T).

Nitrincola alkalilacustris sp. nov. and Nitrincola schmidtii sp. nov., alkaliphilic bacteria isolated from soda pans, and emended description of the genus Nitrincola.

Three alkaliphilic and halotolerant bacterial strains, designated ZV-19T, R4-8T and S4-12, were isolated from the water of soda pans located in the Kiskunság National Park, Hungary. Cells of all three strains were Gram-staining-negative, rod-shaped, motile and non-endospore-forming. They were facultatively anaerobic, and oxidase- and catalase-positive. Their major isoprenoid quinone was Q-8, and their predominant fatty acids were C18 : 1ω7c, C16 : 1ω7c and C16 : 0. The DNA G+C content was 54.5 mol% in strain ZV-19 T and 45.8 mol% in strain R4-8T. The 16S rRNA gene based phylogenetic analysis showed that all three strains were members of the genus Nitrincola (family Oceanospirillaceae, class Gammaproteobacteria). Strain ZV-19T showed 96.6 and 95.5 % sequence similarities and 19±3 and 18±3 % DNA-DNA relatedness to Nitrincolalacisaponensis DSM 16316T and Nitrincolaalkalisediminis JCM 19317T, respectively. Strains R4-8T and S4-12 exhibited 97.9 and 98.6 % sequence matches and 34±4 and 13±8 % DNA-DNA hybridization values with N. lacisaponensis DSM 16316T and N. alkalisediminis JCM 19317T, respectively. According to the phenotypic, chemotaxonomic and phylogenetic data, the strains studied represent two novel species, Nitrincola alkalilacustris sp. nov. with the type strain ZV-19T (=DSM 29817T=NCAIM B 02612T) and Nitrincola schmidtii sp. nov. with the type strain R4-8T (=DSM 100788T=NCAIM B.02626T). An emended description of the genus Nitrincola is also presented.

Bacillus kiskunsagensis sp. nov., a novel alkaliphilic and moderately halophilic bacterium isolated from soda soil.

An alkaliphilic and moderately halophilic strain characterized by optimal growth at pH 9.0-10.0 and 7 % (w/v) NaCl, and designated B16-24T, was isolated from the rhizosphere soil of the bayonet grass Bolboschoenus maritimus at a soda pond in the Kiskunság National Park, Hungary. Cells of the strain were Gram-staining-positive, non-motile, straight rods, and formed central, ellipsoidal endospores with slightly swollen sporangia. The isolate was facultative anaerobic, catalase positive, oxidase negative, and contained a peptidoglycan of type A1γ based on meso-diaminopimelic acid. Menaquinone-7 (MK-7) was the predominant isoprenoid quinone, and anteiso-C15 : 0 the major cellular fatty acid. The DNA G+C content of strain B16-24T was 36.6 mol%. The 16S rRNA gene-based phylogenetic analysis revealed that the novel isolate had the greatest similarities to the type strains of Bacillus okhensis Kh10-101T (97.8 %), B. akibai 1139T (97.4 %), B. alkalisediminis K1-25T (97.3 %) and B. wakoensis N-1T (97.1 %). The DNA-DNA relatedness of strain B16-24T and the closely related Bacillus species ranged between 24±6 % and 35±3 %. The distinctive phenotypic and genetic results of this study confirmed that strain B16-24T represents a novel species within the genus Bacillus, for which the name Bacillus kiskunsagensis sp. nov. is proposed. The type strain is B16-24T (=DSM 29791T=NCAIM B.02610T).

Deinococcus budaensis sp. nov., a mesophilic species isolated from a biofilm sample of a hydrothermal spring cave.

Following the exposure of a biofilm sample from a hydrothermal spring cave (Gellért Hill, Budapest, Hungary) to gamma radiation, a strain designated FeSTC15-38T was isolated and studied by polyphasic taxonomic methods. The spherical-shaped cells stained Gram-negative, and were aerobic and non-motile. The pH range for growth was pH 6.0-9.0, with an optimum at pH 7.0. The temperature range for growth was 20-37 °C, with an optimum at 28 °C. Phylogenetic analysis based on the 16S rRNA gene sequence of the isolate indicated that the organism belongs to the genus Deinococcus. The highest sequence similarities appeared with Deinococcus hopiensis KR-140T (94.1 %), Deinococcus aquaticus PB314T (93.3 %) and Deinococcus aerophilus 5516T-11T (92.7 %). The DNA G+C content of the novel strain was 68.2 mol%. The predominant fatty acids (>10 %) were iso-C16 : 0 and C16 : 1ω7c, and the cell-wall peptidoglycan type was A3ß l-Orn-Gly2-3, corroborating the assignment of the strain to the genus Deinococcus. Strain FeSTC15-38T contained MK-8 as the major menaquinone and several unidentified phospholipids, glycolipids and phosphoglycolipids. Resistance to gamma radiation (D10) of strain FeSTC15-38T was <3.0 kGy. According to phenotypic and genotypic data, strain FeSTC15-38T represents a novel species for which the name Deinococcus budaensis sp. nov. is proposed. The type strain is FeSTC15-38T (=NCAIM B.02630T=DSM 101791T).

Diversity of extremophilic bacteria in the sediment of high-altitude lakes located in the mountain desert of Ojos del Salado volcano, Dry-Andes.

Ojos del Salado, the highest volcano on Earth is surrounded by a special mountain desert with extreme aridity, great daily temperature range, intense solar radiation, and permafrost from 5000 meters above sea level. Several saline lakes and permafrost derived high-altitude lakes can be found in this area, often surrounded by fumaroles and hot springs. The aim of this study was to gain information about the bacterial communities inhabiting the sediment of high-altitude lakes of the Ojos del Salado region located between 3770 and 6500 m. Altogether 11 sediment samples from 4 different altitudes were examined with 16S rRNA gene based denaturing gradient gel electrophoresis and clone libraries. Members of 17 phyla or candidate divisions were detected with the dominance of Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes. The bacterial community composition was determined mainly by the altitude of the sampling sites; nevertheless, the extreme aridity and the active volcanism had a strong influence on it. Most of the sequences showed the highest relation to bacterial species or uncultured clones from similar extreme environments.

Thermophilic prokaryotic communities inhabiting the biofilm and well water of a thermal karst system located in Budapest (Hungary).

In this study, scanning electron microscopy (SEM) and 16S rRNA gene-based phylogenetic approach were applied to reveal the morphological structure and genetic diversity of thermophilic prokaryotic communities of a thermal karst well located in Budapest (Hungary). Bacterial and archaeal diversity of the well water (73.7 °C) and the biofilm developed on the inner surface of an outflow pipeline of the well were studied by molecular cloning method. According to the SEM images calcium carbonate minerals serve as a surface for colonization of bacterial aggregates. The vast majority of the bacterial and archaeal clones showed the highest sequence similarities to chemolithoautotrophic species. The bacterial clone libraries were dominated by sulfur oxidizer Thiobacillus (Betaproteobacteria) in the water and Sulfurihydrogenibium (Aquificae) in the biofilm. A relatively high proportion of molecular clones represented genera Thermus and Bellilinea in the biofilm library. The most abundant phylotypes both in water and biofilm archaeal clone libraries were closely related to thermophilic ammonia oxidizer Nitrosocaldus and Nitrososphaera but phylotypes belonging to methanogens were also detected. The results show that in addition to the bacterial sulfur and hydrogen oxidation, mainly archaeal ammonia oxidation may play a decisive role in the studied thermal karst system.

Vertical physico-chemical gradients with distinct microbial communities in the hypersaline and heliothermal Lake Ursu (Sovata, Romania).

The effect of vertical physico-chemical stratification on the planktonic microbial community composition of the deep, hypersaline and heliothermal Lake Ursu (Sovata, Romania) was examined in this study. On site and laboratory measurements were performed to determine the physical and chemical variables of the lake water, and culture-based and cultivation-independent techniques were applied to identify the members of microbial communities. The surface of the lake was characterized by a low salinity water layer while the deepest region was extremely saline (up to 300 g/L salinity). Many parameters (e.g. photosynthetically active radiation, dissolved oxygen concentration, pH, redox potential) changed dramatically from 2 to 4 m below the water surface in conjunction with the increasing salinity values. The water temperature reached a maximum at this depth. At around 3 m depth, there was a water layer with high (bacterio) chlorophyll content dominated by Prosthecochloris vibrioformis, a phototrophic green sulfur bacterium. Characteristic microbial communities with various prokaryotic taxa were identified along the different environmental parameters present in the different water layers. Some of these bacteria were known to be heterotrophic and therefore may be involved in the decomposition of lake organic material (e.g. Halomonas, Idiomarina and Pseudoalteromonas) while others in the transformation of sulfur compounds (e.g. Prosthecochloris). Eukaryotic microorganisms identified by molecular methods in the lake water belonged to genera of green algae (Mantionella and Picochlorum), and were restricted mainly to the upper layers.

Taxonomic diversity of extremophilic prokaryotes adapted to special environmental parameters in Hungary: a review.

The taxonomic and metabolic diversity of prokaryotes and their adaptability to extreme environmental parameters have allowed extremophiles to find their optimal living conditions under extreme conditions for one or more environmental parameters. Natural habitats abundant in extremophilic microorganisms are relatively rare in Hungary. Nevertheless, alkaliphiles and halophiles can flourish in shallow alkaline lakes (soda pans) and saline (solonetz) soils, where extreme weather conditions favor the development of unique bacterial communities. In addition, the hot springs and thermal wells that supply spas and thermal baths and provide water for energy use are suitable colonization sites for thermophiles and hyperthermophiles. Polyextremophiles, adapted to multiple extreme circumstances, can be found in the aphotic, nutrient-poor and radioactive hypogenic caves of the Buda Thermal Karst, among others. The present article reviews the organization, taxonomic composition, and potential role of different extremophilic bacterial communities in local biogeochemical cycles, based on the most recent studies on extremophiles in Hungary.

Taxonomic diversity and environmental tolerance of cultivable extremophilic bacteria from a high-altitude meltwater pond on Ojos del Salado (Chile).

Earth harbors unique environments where only microorganisms adapted to extreme conditions, known as extremophiles, can survive. This study focused on a high-altitude meltwater pond, located in the Puna de Atacama, Dry Andes. The extremophilic bacteria of this habitat must adapt to a range of extremities, including cold and dry climate, high UV radiation, high daily temperature fluctuations, low-nutrient availability, and negative water balance. This study aimed to explore the taxonomic diversity of cultivable extremophilic bacteria from sediment samples of a desiccated, high-altitude, meltwater pond using media with different organic matter contents and different incubation temperatures. Based on the 16S rRNA gene sequence analysis, the isolates were identified as members of the phyla Actinobacteria, Proteobacteria, and Firmicutes. The most abundant genera were Arthrobacter and Pseudoarthrobacter. The isolates had oligocarbophilic and psychrotrophic properties, suggesting that they have adapted to the extreme environmental parameters of their natural habitats. The results indicate a positive correlation between nutrient concentration and temperature tolerance.

Soil bacterial communities affected by land-use types in a small catchment area of the Balaton Uplands (Hungary).

Changes resulting from different tillage practices can affect the structure of microbial communities, thereby altering soil ecosystems and their functioning. The aim of this study was to explore and compare the physical, chemical properties and bacterial community composition of soils from different land use types (forest, grassland, vineyard, and arable field) in a small catchment. 16S rRNA gene-based amplicon sequencing was used to reveal the taxonomic diversity of summer and autumn soil samples taken from two different slope positions. The greater the anthropogenic impact was on the type of land use, the greater the change was in soil physical and chemical parameters. All sample types were dominated by the phyla Pseudomonadota, Acidobacteriota, Actinobacteriota, Bacteroidota and Verrucomicrobiota. Differences in the relative abundance of various bacterial taxa reflected the different land use types, the seasonality, and the topography. These diversity changes were consistent with the differences in soil properties.

Response of the metabolic activity and taxonomic composition of bacterial communities to mosaically varying soil salinity and alkalinity.

Soil salinity and sodicity is a worldwide problem that affects the composition and activity of bacterial communities and results from elevated salt and sodium contents. Depending on the degree of environmental pressure and the combined effect of other factors, haloalkalitolerant and haloalkaliphilic bacterial communities will be selected. These bacteria play a potential role in the maintenance and restoration of salt-affected soils; however, until recently, only a limited number of studies have simultaneously studied the bacterial diversity and activity of saline-sodic soils. Soil samples were collected to analyse and compare the taxonomic composition and metabolic activity of bacteria from four distinct natural plant communities at three soil depths corresponding to a salinity‒sodicity gradient. Bacterial diversity was detected using 16S rRNA gene Illumina MiSeq amplicon sequencing. Community-level physiological profiles (CLPPs) were analysed using the MicroResp™ method. The genus-level bacterial composition and CLPPs differed significantly in soils with different alkaline vegetation. The surface soil samples also significantly differed from the intermediate and deep soil samples. The results showed that the pH, salt content, and Na+ content of the soils were the main edaphic factors influencing both bacterial diversity and activity. With salinity and pH, the proportion of the phylum Gemmatimonadota increased, while the proportions of Actinobacteriota and Acidobacteriota decreased.

Changes in the taxonomic composition of soil bacterial communities under different inter-row tillage managements in a sloping vineyard of the Balaton Uplands (Hungary).

The common grape (Vitis vinifera L.) has been cultivated for thousands of years. Nowadays, it is cultivated using a variety of tillage practices that affect the structure of the soil microbial communities and thus the health of the vine. The aim of this study was to explore and compare the effects of tillage (shallow tillage with bare soil) and no-tillage (perennial grass cover) practices on soil physical and chemical properties and soil bacterial community diversities in a small catchment. Soil samples were taken in July and October 2020 at different slope positions of two vineyards exposed to erosion. The two sampling sites were separated by the agricultural inter-row management type: tilled and no-tilled slopes. The taxonomic diversity of bacterial communities was determined using 16S rRNA gene-based amplicon sequencing method on Illumina MiSeq platform. Based on the examined soil properties, the sampling areas were separated from each other according to the positions of the upper and lower slopes and the sampling times. Both the tilled and no-tilled soil samples were dominated by sequences assigned to phyla Pseudomonadota, Acidobacteriota, Bacteroidota, Verrucomicrobiota, Actinobacteriota, and Gemmatimonadota. The results showed that tillage had no significant effect compared to the no-tilled samples in the studied area. Water runoff and seasonally changed soil physical and chemical properties affected mainly the bacterial community structures.

Calcium carbonate precipitating extremophilic bacteria in an Alpine ice cave.

Extensive research has provided a wealth of data on prokaryotes in caves and their role in biogeochemical cycles. Ice caves in carbonate rocks, however, remain enigmatic environments with limited knowledge of their microbial taxonomic composition. In this study, bacterial and archaeal communities of the Obstans Ice Cave (Carnic Alps, Southern Austria) were analyzed by next-generation amplicon sequencing and by cultivation of bacterial strains at 10 °C and studying their metabolism. The most abundant bacterial taxa were uncultured Burkholderiaceae and Brevundimonas spp. in the drip water, Flavobacterium, Alkanindiges and Polaromonas spp. in the ice, Pseudonocardia, Blastocatella spp., uncultured Pyrinomonadaceae and Sphingomonadaceae in carbonate precipitates, and uncultured Gemmatimonadaceae and Longimicrobiaceae in clastic cave sediments. These taxa are psychrotolerant/psychrophilic and chemoorganotrophic bacteria. On a medium with Mg2+/Ca2+ = 1 at 21 °C and 10 °C, 65% and 35% of the cultivated strains precipitated carbonates, respectively. The first ~ 200 µm-size crystals appeared 2 and 6 weeks after the start of the cultivation experiments at 21 °C and 10 °C, respectively. The crystal structure of these microbially induced carbonate precipitates and their Mg-content are strongly influenced by the Mg2+/Ca2+ ratio of the culture medium. These results suggest that the high diversity of prokaryotic communities detected in cryogenic subsurface environments actively contributes to carbonate precipitation, despite living at the physical limit of the presence of liquid water.

Planktonic bacterial community composition of an extremely shallow soda pond during a phytoplankton bloom revealed by cultivation and molecular cloning.

Böddi-szék is one of the shallow soda ponds located in the Kiskunság National Park, Hungary. In June 2008, immediately prior to drying out, an extensive algal bloom dominated by a green alga (Oocystis submarina Lagerheim) was observed in the extremely saline and alkaline water of the pond. The aim of the present study was to reveal the phylogenetic diversity of the bacterial communities inhabiting the water of Böddi-szék during the blooming event. Using two different selective media, altogether 110 aerobic bacterial strains were cultivated. According to the sequence analysis of the 16S rRNA gene, most of the strains belonged to alkaliphilic or alkalitolerant and moderately halophilic species of the genera Bacillus and Gracilibacillus (Firmicutes), Algoriphagus and Aquiflexum (Bacteroidetes), Alkalimonas and Halomonas (Gammaproteobacteria). Other strains were closely related to alkaliphilic and phototrophic purple non-sulfur bacteria of the genera Erythrobacter and Rhodobaca (Alphaproteobacteria). Analysis of the 16S rRNA gene-based clone library indicated that most of the total of 157 clone sequences affiliated with the anoxic phototrophic bacterial genera of Rhodobaca and Rhodobacter (Alphaproteobacteria), Ectothiorhodospira (Gammaproteobacteria) and Heliorestis (Firmicutes). Phylotypes related to the phylum Bacteroidetes formed the second most abundant group. Clones related to the mainly anaerobic and alkaliphilic bacterial genera of Anoxynatronum (Firmicutes), Spirochaeta (Spirochaetes) and Desulfonatronum (Deltaproteobacteria) were also abundant. Further clone sequences showed less than 95 % similarity values to cultivated species of the phyla Actinobacteria, Cyanobacteria, Deinococcus-Thermus, Fibrobacteres, Gemmatimonadetes and Lentisphaerae.

Phylogenetic diversity of bacterial and archaeal communities inhabiting the saline Lake Red located in Sovata, Romania.

Lake Red is one of the saline lakes which were formed as a consequence of salt massif dissolution at the foot of the Gurghiu Mountains (Central Romania) at the end of the nineteenth century. The lake water had approximately 15 % w/v salt content. Phylogenetic diversity of prokaryotes inhabiting the water and sediment of the lake was studied using cultivation and cultivation-independent methods following a sampling in spring 2009. According to the results of 16S rRNA gene-based denaturing gradient gel electrophoresis (DGGE), the richness of Bacteria was higher than Archaea on the basis of the number and position of dominant bands in the gel. Sequences from DGGE bands were affiliated with Gammaproteobacteria (Halomonas and Alkalilimnicola) and Bacteroidetes (Psychroflexus) as well as Euryarchaeota. Cultivation from five different saline media resulted in 101 bacterial strains of which Gammaproteobacteria (Halomonas, Marinobacter and Salinivibrio) were the most abundant. Firmicutes (Bacillus) and Alphaproteobacteria (Aurantimonas and Roseovarius) were also identified among the isolated strains. The 16S rRNA genes from 82 bacterial and 95 archaeal clones were also phylogenetically analyzed. Bacterial clones were related to various genera of Gammaproteobacteria (Alkalilimnicola, Alkalispirillum, Arhodomonas, Halomonas, Saccharospirillum), Bacteroidetes (Gracilimonas, Psychroflexus) and Alphaproteobacteria (Oceanicola, Roseinatronobacter, Roseovarius). All of the archaeal clones sequenced corresponded to a homologous cluster affiliated with Halopelagius.