Diversity of bacteria and archaea from two shallow marine hydrothermal vents from Vulcano Island

Garabed Antranikian, Marcel Suleiman, Christian Schäfers, Michael W. W. Adams, Simonetta Bartolucci, Jenny M. Blamey, Nils-Kåre Birkeland, Elizaveta Bonch-Osmolovskaya, Milton S. da Costa, Don Cowan, Michael Danson, Patrick Forterre, Robert Kelly, Yoshizumi Ishino, Jennifer Littlechild, Marco Moracci, Kenneth Noll, Tairo Oshima, Frank Robb, Mosè Rossi, Helena Santos, Peter Schönheit, Reinhard Sterner, Rudolf Thauer, Michael Thomm, Jürgen Wiegel, Karl Otto Stetter

To obtain new insights into community compositions of hyperthermophilic microorganisms, defined as having optimal growth temperatures of 80 °C and above, sediment and water samples were taken from two shallow marine hydrothermal vents (I and II) with temperatures of 100 °C at Vulcano Island, Italy. A combinatorial approach of denaturant gradient gel electrophoresis (DGGE) and metagenomic sequencing was used for microbial community analyses of the samples. In addition, enrichment cultures, growing anaerobically on selected polysaccharides such as starch and cellulose, were also analyzed by the combinatorial approach. Our results showed a high abundance of hyperthermophilic archaea, especially in sample II, and a comparable diverse archaeal community composition in both samples. In particular, the strains of the hyperthermophilic anaerobic genera Staphylothermus and Thermococcus, and strains of the aerobic hyperthermophilic genus Aeropyrum, were abundant. Regarding the bacterial community, ε-Proteobacteria, especially the genera Sulfurimonas and Sulfurovum, were highly abundant. The microbial diversity of the enrichment cultures changed significantly by showing a high dominance of archaea, particularly the genera Thermococcus and Palaeococcus, depending on the carbon source and the selected temperature.