台灣地熱區 Thermus 屬嗜熱菌生物多樣性之研究

This study focuses on thermophiles isolated from geothermal area in Taiwan. A group of thermophiles similar to genus Thermus which have been isolated from 13 hot springs in Taiwan. They form yellow pigmented colony and the cells of these organisms are Gram-negative, rod-shaped, non-motile, non-spore forming, and can grow at 70 oC. After 16S rDNA amplifications and sequence analyses, the blasting results indicate that these thermophiles can be divided into two groups. The 16S rDNA sequences of the first group isolates exhibit highest similarity value ( above 99 % ) to the related Thermus species. Based on physiological tests and fatty acid analyses, these thermophiles similar to Thermus species which have been named and published formally, are belonged to T. aquaticus NTU-103, T. thermophilus NTU-1534 and NTU-1651；T. oshimai NTU-58、NTU-63 and NTU-88；T. brockianus NTU-9、NTU-153 and NTU-154。 The 16S rDNA similarity of the other group of isolates are between 96% to 98% and DNA-DNA hybridizations are below 70 %. Based on physiological tests, fatty acid analyses, biochemical assays and genetics analyses, these thermophiles may be new species of genus Thermus. T. thermophilus HB8 related isolates NTU-56, NTU-62 and NTU-158 are named T. taipeiensis; T. scotoductus ITI-252 related Isolate NTU-24 is named T. wuariensis; another isolates NTU-559, NTU-1307 and NTU-1597 which are similar to T. brockainus YS038 have not been named. In this study, hundred strains of genus Thermus had been isolated and identified: four species of genus Thermus which are named and published formally are T. aquaticus, T. oshimai, T. brockianus and T. thermophilus, and three new species including T. taipeiensis, T. wuariensis and unnamed Thermus sp. are found in geothermal area of Taiwan. Besides, T. taiwanensis is one of new species of Thermus that is identified but not published formally. Thus, the genus Thermus exists in neutral or slightly alkaline hot springs in Taiwan and shows biodiversity.