玉山國家公園高海拔山區土壤中低溫細菌多樣性之研究

The biodiversity of psychrotrophic bacteria from the soil of high-elevation regions in Yushan National Park

孫君寧(Jun-Ning Sun)

指導教授 ： 謝文陽

國立臺灣大學/理學院/海洋研究所/碩士(2017年)

https://doi.org/10.6342/NTU201703004

摘要

地球生物圈有大部分屬於長年溫度低於5°C的寒冷環境，包含占全球陸地面積共約25 %的高山和極地以及深海等；前人已從這些寒冷環境中分離出很多低溫細菌 (psychrotrophs)。臺灣因位處亞熱帶，無長年低溫環境，但玉山國家公園高海拔區域 (海拔3,000公尺以上) 屬於寒帶氣候區，應不乏低溫細菌的存在。本研究的目的在於調查玉山高海拔區域土壤中低溫細菌的組成及多樣性，並發掘可能存在此間新穎低溫細菌。土壤樣本採自玉山主、北峰 (海拔約3,600 – 3,700公尺) 和西峰 (海拔約3,402 – 3,518公尺) 具有不同植被地區。本研究先以平板培養法進行菌株計數及分離，之後進行菌株表型特徵檢測以及16S rRNA基因序列定序，並據以利用neighbor-joining演算法繪製親緣關係樹。結果顯示玉山高海拔區域土壤中低溫細菌數介於2.8 × 106 – 3.5 × 107 (CFU/g wet wt.) 之間，且分離株以耐冷細菌為主，佔97.1 %。16S rRNA序列定序結果顯示所有分離株分成Proteobacteria, Firmicutes, Actinobacteria 和 Bacteroidetes四門，分別佔分離株86.7 %、9.5 %、1.9 %、1.9 %；所有分離株可進一步分成Pseudomonas, Janthinobacterium, Rahnella, Rouxiella, Acinetobacter, Duganella, Flavobacterium, Stenotrophomonas, Collimonas, Variovorax, Luteibacter, Dyella, Caballeronia, Serratia, Arthrobacter, Paenibacillus, Rhodococcus, Oerskovia 18屬，其中以 Pseudomonas為最優勢菌屬 (45.7%)，其次依序為Rahnella (11.4%)和 Janthinobacterium (9.5%)。研究結果顯示，西峰區域菌屬多樣性較高，共分得15屬，且Pseudomonas廣泛分佈於玉山高海拔區域土壤中。此外，菌株H2與其相近標準株序列相似度低於97.0 %，具有發表為新種之潛力，依據親緣關係樹推測該菌株可能為Glaciimonas屬新種。

關鍵字

低溫細菌 ； Glaciimonas ； Pseudomonas ； 玉山國家公園 ； 細菌多樣性 ； 細菌組成

並列摘要

Most of the Earth’s biosphere is permanently cold environment, which temperature is lower than 5 °C, including alpine and polar regions which constitute 25 % of the world’s land surface area, and deep sea, etc. Many psychrotrophs have been isolated from these cold environments. There isn’t any permanently cold environment in Taiwan, for the reason that Taiwan is situated in the subtropical zone. However, the high elevation regions (over 3,000 m) in the Yushan National Park are classified as frigid zones. Therefore, psychrotrophs may abundantly exist in those cold habitats. The purpose of this study was to investigate the compositions and diversity of psychrotrophs in the soil of the high elevation regions of Yushan. Another aim was to find out the novel psychrotrophs existing in the soil of the high elevation regions of Yushan. The soil samples were collected from the different vegetation in the regions of Main, North (3,600 – 3,700 m) and West Peaks (3,402 – 3,518 m) of Yuhsan. This study was conducted using bacterial enumeration and isolation by plate method, detecting the phenotypic characteristics, and the 16S rRNA gene sequences, and constructing the phylogenetic tree by neighbor-joining method. The results revealed that the bacterial abundance of psychrotrophs in the soil of the high elevation regions of Yushan ranged from 2.8 × 106 to 3.5 × 107 (CFU/g wet wt.). About 97 % of isolates were psychrotolerant bacteria. Analysis of the 16S rRNA sequences revealed that 86.7 %, 9.5 %, 1.9 % and 1.9 % of isolates could be divided to four phyla namely Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, respectively. The isolates further distributed into 18 genera, Pseudomonas, Janthinobacterium, Rahnella, Rouxiella, Acinetobacter, Duganella, Flavobacterium, Stenotrophomonas, Collimonas, Variovorax, Luteibacter, Dyella, Caballeronia, Serratia, Arthrobacter, Paenibacillus, Rhodococcus, Oerskovia. In this study, Pseudomonas was the predominant genus (45.7%), follwed by Rahnella (11.4 %) and Janthinobacterium (9.5 %). The result of psychrotrophs composition revealed that the diversity of genera in the regions of West Peak (15 genera) was higher than that in the regions of Main and North Peaks. The result also indicated that Pseudomonas widely distributed in the soil of the high elevation regions of Yushan. Additionally, the sequences similarity of strain H2 in this study and its related type species was lower than 97 %. It meant that strain H2 might have the potential to be proposed as a novel species. According to the result of phylogenetic tree, strain H2 might be a novel species of the genus Glaciimonas.

並列關鍵字

psychrotrophs ； Glaciimonas ； Pseudomonas ； Yushan National Park ； bacterial diversity ； bacterial composition

參考文獻

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