Geomicrobiology of black sediments in Vantului Cave (Romania): preliminary results

Five species of bacteria and one species of fungus have been identified from the black sediments of Vantului Cave, Romania, using molecular methods. Three of the bacterial species (Hyphomicrobium sp., Pedomicrobium fusiforme, Pedomicrobium manganicum) and the fungus Cladosporium spp. are known to mediate the oxidation and precipitation of manganese in different environments, by enyzmatic or nonenzymatic mechanisms. Sphingomonas mali could possibly be another bacterium that contributes to the manganese precipitation in Vantului Cave. This biologically mediated process is likely to be controlled by the pH and/or Eh conditions existing within the subterranean stream environment. Additionally, these microorganisms are implicated in the retention of some rare earth elements within the black sediments.