台灣周邊海域新穎變形菌的分離及分類研究

Abstract

海洋細菌係指生活在海洋環境包括海水、沉積物或其他海洋相關環境中的微生物，其中變形菌門(Proteobacteria)是海洋細菌中數量優勢的一群細菌。為探討台灣沿岸海域新穎海洋細菌的分類，本研究以數種不同增菌培養法分離出細菌分離株，再利用分子方法初步鑑定菌種類別，分子鑑定係以細菌16S rRNA基因序列的相似性閾值98.7%為判定標準，經過初步鑑篩選出可能為新型菌種的9株分離株，這些新菌株應歸屬為變形菌門，其中1株屬於甲型變形菌綱 (Alphaproteobacteria)，其他則屬於丙型變形菌綱 (Gammaproteobacteria)，另外，又將2種分類地位有疑義的菌種從新分類。 本研究顯示，兩株瓊脂分解菌 (AAM1T和AAT1T)，可以將其分類為一個新屬內的兩新種；屬於丙型變形菌綱中源洋菌科(Idiomarinaceae)內的AIT1T菌株，可以被分類為一個新屬新種；一株屬於甲型變形菌綱紅螺菌科(Rhodospirillaceae)中的革蘭氏陰性異營海洋細菌（TT1T），在本研究的多相分類學資料的基礎上，TT1T菌株可以被分類為一個新屬新種；兩株革蘭氏陰性、異營性、好氧，海洋細菌(KT1T和KM1T)，可以將其分類為Kangiella屬內兩新種；從室溫下儲存7年以上的久置海水樣品中所分離出來的菌株SPT1T，在本研究中獲得的多相分類學數據指出菌株SPT1T可被分類為Spongiibacter屬內的新種；從台灣高雄東沙島潟湖沉積物中分離得到的DM1和DM2T菌株，以系統發育數據和化學分類學、生理學和形態學等特徵的數據支持，來提出一個新屬新種的建立；在系統發生學的研究中，[Glaciecola] lipolytica和[Aestuariibacter] litoralis兩菌種的分類並不適切，根據充分的資料，對[Glaciecola] lipolytica和[Aestuariibacter] litoralis的重新分類，並提出了一個新的屬，以更恰當地區分Glaciecola屬和Aestuariibacter屬內的已知菌種。

Marine bacteria are the microorganisms living in seawater, sediments and marine environments. The phylum Proteobacteria is one of the dominant groups in marine bacteria. To investigate the classification of novel marine bacteria in the coastal waters of Taiwan, bacterial isolates were isolated using several different enrichment culture methods and the bacterial species categories were initially identified using molecular methods. A value of less than 98.7% in 16S rRNA gene sequence similarity that is the criteria for determination was used for molecular identification. After preliminary screening, 9 isolates that could be classified as novel species were selected. These novel strains were all classified to be Proteobacteria; one of them belonged to Alphaproteobacteria and the others belonged to Gammaproteobacteria. In addition, this study also reclassify two species that are in doubt about their taxonomic status. This study shows that two agarolytic strains, AAM1T and AAT1T, could be classified as representatives of two novel species in a new genus. The strain AIT1T which belongs to Idiomarinaceae in the class Gammaproteobacteria and could be classified as the representative of a novel genus and species. A Gram-negative, heterotrophic, marine bacterium, designated strain TT1T, which belongs to Rhodospirillaceae in the class Alphaproteobacteria. On the basis of the polyphasic taxonomic data from this study, strain TT1T is considered to represent a novel species within a novel genus. Two Gram-negative, heterotrophic, aerobic, marine bacterial strains, designated KT1T and KM1T, are described. They could be classified as representatives of two novel Kangiella species. A bacteria strain designated SPT1T which was isolated from an aged-seawater sample and stored at room temperature for more than 7 years. Polyphasic taxonomic data obtained from this study indicated that strain SPT1T could be classified as a novel Spongiibacter species. Strains DM1 and DM2T which were isolated from lagoon sediments of Dongsha Island, Kaohsiung, Taiwan. The phylogenetic data and those from chemotaxonomic, physiological and morphological characterizations support the establishment of novel species and genus for the two strains. In phylogenetic studies, the classification of [Glaciecola] lipolytica and [Aestuariibacter] litoralis was unsuitable, and based on sufficient data, a reclassification of [Glaciecola] lipolytica and [Aestuariibacter] litoralis was made and a new genus is proposed to more appropriately accommodate the recognized species of the genera Glaciecola and Aestuariibacter.