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- Author or Editor: K. Márialigeti x
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Atrazine is a frequently detected pollutant in agricultural soils, groundwater and surface waters. Microbial degradation was confirmed in soils, and recently several atrazine-degrading bacteria have been isolated. Degradation in aquifers, however, is not well understood, and to date, atrazine degraders have not been isolated from water. In the present study, the impact of atrazine was assessed in agricultural soil and river sediment and the composition of the atrazine-degrading bacterial community in the soil and sediment was compared. Atrazine pollution increased the number and diversity of the endogenous atrazine degraders in both environments. Proteobacteria were predominant atrazine degraders in soils, whereas the community of atrazine-degrading bacteria in sediment consisted mostly of coryneforms.
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.
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.
The aim of the present work was to compare the microbial communities of a mesophilic and a thermophilic pilot scale anaerobe sludge digester. For studying the communities cultivation independent chemotaxonomical methods (RQ and PLFA analyses) and T-RFLP were applied. Microbial communities of the mesophilic and thermophilic pilot digesters showed considerable differences, both concerning the species present, and their abundance. A Methanosarcina sp. dominated the thermophilic, while a Methanosaeta sp. the mesophilic digester among Archaea. Species diversity of Bacteria was reduced in the thermophilic digester. Based on the quinone patterns in both digesters the dominance of sulphate reducing respiratory bacteria could be detected. The PLFA profiles of the digester communities were similar though in minor components characteristic differences were shown. Level of branched chain fatty acids is slightly lower in the thermophilic digester that reports less Gram positive bacteria. The relative ratio of fatty acids characteristic to Enterobacteriaceae, Bacteroidetes and Clostridia shows differences between the two digesters: their importance generally decreased under thermophilic conditions. The sulphate reducer marker (15:1 and 17:1) fatty acids are present in low quantity in both digesters.
Karst areas have great environmental importance as sources of subsurface water and often maintain very sensitive ecosystems. In recent years, increasing number of microbiological studies focused on the bacterial communities of karst soils. In this study, diversity examinations on two distinct Hungarian karst areas, Aggtelek and Tapolca, were performed using parallel cultivation and molecular cloning methods. The phylogenetic affiliation of bacterial strains and molecular clones was determined based on their 16S rRNA gene sequences. Bacterial isolates were identified as members of the phyla Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes. Besides the taxa identified by cultivation, members of the phyla Chloroflexi, Cyanobacteria, Acidobacteria, Verrucomicrobia, and Gemmatimonadetes were detected by the cloning. The difference in the composition of soil bacterial communities was related to geographic locations and soil types. Both the highest and the lowest bacterial diversities were detected in samples from Aggtelek National Park, characterized by Leptic Luvisol and Rendzic Leptosol soil types. The difference in the composition of bacterial communities between Rendzic Leptosol and Leptic Phaeozem soil types at Tapolca could be the result of human impacts.
Water samples of ten mineral water springs at Miercurea Ciuc (Csíkszereda) region (Romania) were examined during 2005–2006 using cultivation-dependent microbiological methods. The results of standard hygienic bacteriological tests showed that the Hargita Spring had perfect and five other springs had microbiologically acceptable water quality (Zsögöd-, Nagy-borvíz-, Taploca-, Szentegyháza- and Lobogó springs). The water of Borsáros Spring was exceptionable (high germ count, presence of Enterococcus spp.).Both standard bacteriological and molecular microbiological methods indicated that the microbiological water quality of the Szeltersz-, Nádasszék- and Délő springs was not acceptable. Bad water quality resulted from inadequate spring catchment and hygiene (low yield, lack of runoff, negligent usage of the springs, horse manure around the spring).The 16S rRNA gene-based identification of strains isolated on standard meat-peptone medium resulted in the detection of typical aquatic organisms such as Shewanella baltica, Aeromonas spp., Pseudomonas veronii, Psychrobacter sp,. Acinetobacter spp. and allochthonous microbes, like Nocardia, Streptomyces, Bacillus, Microbacterium , and Arthrobacter strains indicating the impact of soil. Other allochthonous microbes, such as Staphylococcus spp., Micrococcus sp., Lactococcus sp., Clostridium butyricum, Yersinia spp., Aerococcus sp., may have originated from animal/human sources.
The blowfly Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) is the primary agent of cutaneous myiasis of sheep in northern Europe, southern Africa, Australia and New Zealand. As the application of chemicals has several disadvantages, alternative control measures of traumatic myiasis of livestock must be developed. In this study, the use of entomopathogenic nematodes (EPNs) as potential biocontrol agents against second instar larvae of Lucilia sericata was considered. The following nematode species were tested: Heterorhabditis bacteriophora (IS 5, HHU 1, Hmo1, HNC 1, HAZ 36, Hbrecon, HHU 2, HAZ 29, HHP 88, HHU 3, HHU 4 and HGua), Steinernema intermedia, NC513 strain of S. glaserii, S. anomali, S. riobrave, Steinernema sp. and 5 strains of S. feltiae (22, Vija Norway, HU 1, scp, and IS 6). None of the examined EPN species or strains showed larvicidal efficacy at 37°C (no killing effect was observed in the case of the two heat-tolerant strains - H. bacteriophora and S. feltiae) against L. sericata larvae. At lower temperatures (20°C and 25°C) only strainsof S. feltiae were found to be active. The overall odds ratios calculated for L. sericata maggots to contract S. feltiae nematode infection show significant (p < 0.05) effect only in the case of strains HU 1, 22 and IS 6. In the case of strains HU 1 and 22 parasitic forms of S. feltiae could be detected in the dead larvae of L. sericata. Strain IS 6 (and also Vija Norway at 20°C) penetrated and killed fly larvae, but only adult forms of the nematode occurred in the cadavers.