Seasonal and spatial variability of sediment bacterial communities inhabiting the large shallow Lake Balaton

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.

Homogeneous microbial diversity in the upper sediment layers of a shallow lake

“…Baikal, Constance, Kinneret; Pester et al 2004, Shubenkova et al 2005, Schwarz et al 2007, Deutzmann et al 2011) depends on the depth of the lake and, in the case of large lakes, the shape of the lake basin, leading to diverse conditions in the basins of these lakes. In studies of shallow and large lakes, the morphometry of which is more complex (such as Lake Taihu in China or Lake Balaton in Hungary), distinct bacterial communities have been observed , Tian et al 2009, Szabó et al 2011 in different basins with different sediment properties. Lake Võrtsjärv is more round in shape and the bottom areas are dominated by such sediments as organic (lake mud or sapropel), carbonaceous (lake marl), and terrigenous (gravel, sand, silt, clay) deposits.…”

Gut content microbiota of introduced bigheaded carps ( Hypophthalmichthys spp.) inhabiting the largest shallow lake in Central Europe

“…It has a surface area of 596 km 2 and an average depth of about 3 m (Szabó et al, 2011). Bigheaded carps and water samples were collected from the eastern basin of Lake Balaton in April, May, June, September and October 2013.…”

Seasonal and size-related variation of subcellular biomarkers in quagga mussels (Dreissena bugensis) inhabiting sites affected by moderate contamination with complex mixtures of pollutants

“…Taking into account local characteristics of the sampling sites, due to relatively low variations 28 of basic environmental parameters (Tátrai et al 2008;Szabó et al 2011), the selected sites 29 may differ only in the contamination status mainly deriving from the temporal ship traffic 30 present from spring to late autumn. The sampling areas, according to previous sediment 31 quality studies, are slightly polluted by metals and PAHs as none of the investigated 32 contaminants exceeded the threshold effect concentration (TEC) below which no biological 33 effect can be expected.…”