台灣地熱區 Thermus 屬嗜熱菌生物多樣性之研究

Abstract

本研究針對台灣地熱區進行嗜熱性微生物之研究。由採集的13座溫泉樣區液中，篩選出一群與嗜熱性細菌 Thermus 屬相似，可生長在70 oC 的黃色菌株。經由形態觀察，為革蘭氏陰性、細胞呈桿狀、不具運動性、無內孢子。再經由細菌 16S rDNA 片段的擴增與序列比對，發現部分菌株的 16S rDNA 序列與國外已發表之 Thermus 屬菌種的相似度高達 99 % 以上，再藉由基本生理測試及脂肪酸組成分析，將此群菌株分別歸屬於：T. aquaticus NTU-103；T. thermophilus NTU-1534及NTU-1651；T. oshimai NTU-58、NTU-63 及 NTU-88；T. brockianus NTU-9、NTU-153 及 NTU-154。 另一群菌株的 16S rDNA 片段序列與國外已發表之 Thermus 屬菌種的相似度介於 96 至 98 % 之間，且DNA-DNA 雜合反應皆低於 70 %。由形態觀察、生理、生化及遺傳特性分析，可以將之歸為 Thermus 屬的新種菌株。與 T. thermophilus HB8 較相近的菌株NTU-56、NTU-62 及 NTU-158 被命名為 T. taipeiensis；與 T. scotoductus 較相近的菌株NTU-24 被命名為 T. wuraiensis；與T. brockianus 較相近的菌株NTU-559、NTU-1307 及 NTU-1597則尚未被命名。 目前國外命名且正式發表的 Thermus 屬菌種有 9 種，本研究發現台灣地熱區Thermus 屬菌株中包含4 種與國外發表的相同菌種以及3種本土新穎菌種 T. taipeiensis、T. wuariensis及未命名的 Thermus sp.，再加上本研究室之前已鑑定但未發表菌株 T. taiwanensis，可知台灣溫泉中的Thermus 屬菌相豐富且具有生物多樣性，並廣泛分布在台灣北部、中部及東部偏中性或是微鹼性溫泉中。

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.