A halophilic thermophilic bacterium isolated from a coastal hot spring in Lutao, Taiwan

SUMMARY: A heterotrophic, moderately thermophilic bacterial strain, designated strain T501, was isolated from a hot spring on the coast of Lutao, Taiwan. This bacterial strain was a strictly aerobic, Gram-negative rod, normally 0.6-0.7 μm in diameter and 4-10 μm in length, and motility was achieved by one to several lateral flagella. Its minimum and maximum growth temperatures were approximately 30 and 60 °C, respectively, with an optimal temperature at about 50 °C. The G + C ratio of its DNA was 38.1 mol%. Strain T501 tolerated a pH range from 6 to 9. It was halophilic, growing optimally in about 2% (w/v) salt, and Na+ was indispensable unless Mg2+ or Ca2+ were available. The addition of either cation to Na--sufficient media significantly enhanced growth. Halophilic heterotrophic bacteria capable of aerobic growth over a temperature range of 40-55 °C have not been reported previously.