Diversity of reed (Phragmites australis) stem biofilm bacterial communities in two Hungarian soda lakes.

From reed biofilm samples of Kelemen-szék (Kiskunság National Park, KNP) and Nagy-Vadas (Hortobágy National Park, HNP) altogether 260 bacterial isolates were gained after serial dilutions and plating onto different media. Following a primary selection 164 strains were investigated by "traditional" phenotypic tests and clustered by numerical analysis. Fifty-six representative strains were selected to ARDRA and 16S rDNA sequence analysis for identification. Strains were identified as members of genera Agrobacterium, Paracoccus, Halomonas, Pseudomonas, Bacillus, Planococcus and Nesterenkonia. The species diversity was also investigated by a cultivation independent method. A clone library was constructed using the community DNA isolated from the biofilm sample of Kelemen-szék. Screening of the 140 bacterial clones resulted in 45 different ARDRA groups. Sequence analysis of the representatives revealed a great phylogenetic diversity. A considerable majority of the clones was affiliated with uncultured bacterial clones (with sequence similarity between 93 and 99%) originating from diverse environmental samples (for example salt marshes, compost or wastewater treatment plants). The DNA sequences of other clones showed the presence of genera Flavobacterium, Sphingobacterium, Pseudomonas and Agrobacterium.