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- Author or Editor: Márton Palatinszky x
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Lake Hévíz is the largest natural thermal lake of Europe, harboring special bacterial communities. The aim of the present study was to gain information about the distribution and species diversity of the sediment microbiota, with special focus on Actinobacteria, by using cultivation-based and -independent molecular methods. Samples from two depths were taken in two different locations in October 2007. 245 strains were isolated, grouped to 85 OTUs by ARDRA, and identified by 16S rDNA sequencing. Most of the strains showed highest sequence similarity with Bacillus and related genera. Strains belonging to the phylum Actinobacteria were identified as members of Arthrobacter, Brachybacterium, Brevibacterium, Curtobacterium, Friedmanniella, Gordonia, Kocuria, Microbacterium, Micrococcus, Micromonospora, Mycobacterium, Rhodococcus, Streptomyces and Williamsia . Two clone libraries were constructed from H3M and H4M samples, providing 288 and 192 clones which were grouped to 150 and 125 OTUs, respectively, by ARDRA. The two most abundant group of the H4M library were OP8-related. The phylum Proteobacteria was represented mostly by δ -Proteobacteria, other relevant groups were Cyanobacteria, Bacteroidetes, Acidobacteria and β -Proteobacteria. The H3M library was dominated by Cyanobacteria, Verrucomicrobia, β -Proteobacteria, γ -Proteobacteria and δ -Proteobacteria. Chloroflexi, Bacteroidetes, Spirochetes and Firmicutes were scarce. Results from the clone libraries were compared to the length-heterogeneity-PCR fingerprints of the communities.
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.
The effect of several easily degradable substrates, such as protein, starch and sunflower oil was investigated on the bacterial community of a laboratory-scale biogas model system. Besides measuring gas yield, Denaturing Gradient Gel Electrophoresis (DGGE), Phospholipids Fatty Acid Analysis (PLFA) for Bacteria and T-RFLP analysis of the mcrA gene for Archaea were used. The community of the examined biogas reactors adapted to the new substrates through a robust physiological reaction followed by moderate community abundance shifts. Gas yield data clearly demonstrated the physiological adaptation to substrate shifts. Statistical analysis of DNA and chemotaxonomic biomarkers revealed community abundance changes. Sequences gained from DGGE bands showed the dominance of the phyla Bacteroidetes and the presence of Firmicutes (Clostridia) and Thermotogae. This was supported by the detection of large amounts of branched 15-carbon non-hydroxy fatty acids in PLFA profiles, as common PLFA markers of the Bacteroidetes group. Minor abundance ratios changes were observed in the case of Archaea in accordance with changes of the fed substrates.
Karst areas belong to the most exposed terrestrial ecosystems, therefore their study have a priority task in Hungary, as well. The aim of this study was to compare the structure, activity and diversity of soil microbial communities from two distinct Hungarian karst areas (Aggtelek NP and Tapolca-basin). Soil samples were taken three times from 6 distinct sites, from different depths. Soil microbial biomass C (MBC), microbial biomass N (MBN), basal respiration (BRESP) and substrate induced respiration (SIR) were measured. The phylogenetic diversity of bacterial communities was compared by Denaturing Gradient Gel Electrophoresis (DGGE). The highest MBC, MBN, BRESP and SIR values were measured in the rendzina soil from Aggtelek. On the basis of biomass and respiration measurements, microbial communities differentiated mainly according to soil depths whereas DGGE profiles of bacterial communities resulted in groups mainly according to sampling sites.