HYPERTHERMOPHILIC LIFE AT DEEP-SEA HYDROTHERMAL VENTS

The discovery of deep-sea hydrothermal vents in 1977 considerably modi fied the views on deepsea biology. For the first time, an ecosystem to tally based on primary production achieved by chemosynthetic bacteria was discovered. Besides the warm vents where dense invertebrate commun ities and their symbiotic bacteria are located, the ''black smokers'' venting fluids at temperatures up to 350 degrees C were also investiga ted by microbiologists. Several strains of hyperthermophilic Archaea ( methanogens, sulfate-reducers, sulfur-reducers) were isolated from smo kers and surrounding materials. Deep-sea isolates that have been total ly described, have been assigned to new species, within genera previou sly found in coastal geothermally heated environments. However, some s pecies appear to exist in both deep and shallow ecosystems. Some deep- sea hyperthermophiles appear to be adapted to hydrostatic pressure and showed a barophilic response. The distribution of hyperthermophiles i n the hot ecosystems of the planet, and their adaptation to pressure a re presented and discussed.