Seasonal and spatial variability of sediment bacterial communities inhabiting the large shallow Lake Balaton |
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Authors: | Gitta Szabó Bernadett Khayer Anna Rusznyák István Tátrai György Dévai Károly Márialigeti Andrea K Borsodi |
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Institution: | 1.Department of Microbiology,E?tv?s Loránd University,Budapest,Hungary;2.Balaton Limnological Research Institute of the Hungarian Academy of Sciences,Tihany,Hungary;3.Department of Hydrobiology,University of Debrecen,Debrecen,Hungary |
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Abstract: | Seasonal studies of surface sediment bacterial communities, from two basins with differing trophic states within Lake Balaton
(Hungary), were carried out using molecular (denaturing gradient gel electrophoresis, DGGE) and cultivation-based techniques.
The presence of polyphosphate accumulates was tested using Neisser staining, and phosphatase activity was investigated on
organic phosphorus (P) compound. Aerobic viable cell counts were significantly higher in the eutrophic than mesotrophic basin
in each season. The lowest viable counts were observed in the autumn and the highest in spring and summer month in both basins.
The DGGE fingerprints of the samples reflected that the composition of sediment bacterial communities in the two basins were
distinct in spring and summer, and similar in autumn, but similarly diverse in all seasons. On the basis of partial 16S rDNA
sequences, the 216 strains were affiliated with six major bacterial lineages: Firmicutes; Actinobacteria, Bacteroidetes, Alphaproteobacteria,
Betaproteobacteria, and Gammaproteobacteria. Common species characterized from both basins constituted up to 66% of all identified
phylotypes. Strains related to Bacillus sp. were dominant in all but one sample. Isolates affiliated with Aeromonas sp. prevailed in the sample taken from the mesotrophic basin in spring. The majority of the strains showed excess poly-P
accumulation. Association of Neisser staining and phosphatase activity test results suggested that excess poly-P accumulation
serves as P storage for sediment bacteria. Our study implied the importance of Firmicutes, Actinobacteria, Alphaproteobacteria,
and Aeromonas species in benthic bacterial P retention. |
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