Isolation and characterization of Thermus thermophilus Gy1211 from a deep-sea hydrothermal vent

We examined a single, non-spore-forming, aerobic, thermophilic strain that was isolated from a deep-sea hydrothermal vent in the Guaymas Basin at a de pth of 2000 m and initially placed in a phenetic group with Thermus scotodu ctus (X-1). We identified this deep-sea isolate as a new strain belonging t o Thermus thermophilus using several parameters. DNA-DNA hybridization unde r stringent conditions showed 74% similarity between the deep-sea isolate a nd T. thermophilus HB-8(T) (T = type strain). Phenotypic characteristics, s uch as the utilization of carbon sources, hydrolysis of different compounds , and antibiotic sensitivity were identical in the two strains. The polar l ipids composition showed that strain Gy1211 belonged to the genus Thermus. The fatty acids composition indicated that this strain was related to the m arine T. thermophilus strain isolated from the Azores. The new isolate T. t hermophilus strain Gy1211 grew optimally at 75 degrees C, pH 8.0, and 2% Na Cl. A hydrostatic pressure of 20 MPa, similar to the in situ hydrostatic pr essure of the deep-sea vent from which the strain was isolated, had no effe ct on growth. Strain HB-8(T), however, showed slower growth under these con ditions.