Investigations on the Danube gravel-biofilm diatom-associated bacterial communities

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Gravel samples were collected from the northern water gaining area of bank wall filtered wells of Budapest at the north-eastern shoreline of Szentendre Island, in the main arm of the Danube river. On the island there are rows of bank wall filtered wells, which supply with drinking water the capital of Hungary. Gravel washing fluid samples were plated onto three different algal media in order to isolate diatom-associated bacterial strains. Isolates were purified and representative strains were selected on the basis of cultural-morphological features, biochemical investigations, and ARDRA. Selected strains were identified by the Biolog phenotypic fingerprint method and by 16S rDNA sequencing. Our results have shown that besides the dominant Pseudomonas Gram-negative genera were Flavimonas, Flavobacterium, Mycoplana, Sinorhizobium, Afipia, Variovorax, Sphingomonas whereas the Gram-positive ones were Streptomyces, Rhodococcus, and Microbacterium. The bacteria isolated were able to utilize such sugars and amino acids as only carbon sources, which have been proved to be among extracellular products of diatoms. Thus it can be supposed that association between diatoms and bacteria is also based upon metabolic interactions.

Original languageEnglish
Pages (from-to)729-742
Number of pages14
JournalBiologia - Section Botany
Issue number4
Publication statusPublished - Jul 1 2003



  • 16S rDNA sequencing
  • Algal-bacterial interaction
  • Biofilm
  • Hungary
  • The Danube river

ASJC Scopus subject areas

  • Ecology
  • Plant Science

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