FIRST ISOLATION OF THERMOPHILIC AEROBIC NON-SPORULATING HETEROTROPHICBACTERIA FROM DEEP-SEA HYDROTHERMAL VENTS

Thermophilic aerobic non-sporulating heterotrophic bacteria were isola ted for the first time from deep-sea hydrothermal vents, Samples were taken at Snakepit (Mid-Atlantic Ridge) and Guaymas Basin (Gulf of Cali fornia). Isolates consisting of pleomorphic rods, single cells or pair s, formed filaments of variable length, and grew at 70 degrees C or so me up to 80 degrees C. They were halotolerant and unable to grow anaer obically, except some strains in the presence of nitrate. A numerical classification based on phenotypic features was performed on the isola tes, including three reference strains Rhodothermus marinus (R-10), Th ermus aquaticus (YT-1) and Thermus scotoductus (X-1) and one yellow pi gmented Thermus strain. Results from unweighted average linkage (UPGMA ) clustering applied to a similarity matrix derived from the simple ma tching (S-SM) coefficient showed the formation of five main clusters w hich were defined for at least 80% similarity, whereas only three isol ates remained outside of the clusters. One reference strain (X-1) clus tered with one isolate at a level of 83% and between 76-78% with other clusters. The other reference strains showed less than 55% similarity with the deep-sea isolates.