The most recent major explosive eruption of the Santorini volcano in Greece (around 3600 years before present) was one of the largest volcanic events known in historical time. The Santorini volcanic field extends 20 km to the northeast as a line of more than 20 submarine cones. The largest of these submarine craters is Kolumbo, a three-km-diameter cone with a 1500 m wide crater at a depth of 505 m below sea level. During a recent marine survey (of the Hellenic Centre for Marine Research in collaboration with the Rhode Island University), a widespread hydrothermal vent field was discovered on the floor of the Kolumbo crater [Sigurdsson et al. 2006]. High temperature venting with fluid temperatures up to 220oC from vent chimneys as well as lower-temperature chimneys and vents (with fluids up to 70oC) were discovered. The exterior of most chimneys is covered with white, grey, and reddish filamentous bacteria. Large areas on the floor of the Kolumbo volcano are covered by reddish bacteria, white and reddish orange bacterial mats that can be characterized as promising targets of high microbial colonisation and hence biotechnological interest. Thus, samples of red and white-grey bacterial mats have been collected for the metagenomic exploration of these newly discovered habitats in collaboration with the Joint Genome Institute, Department of Energy, USA (Dr. Nikos Kyrpides, Head of the Genome Biology Program).
