Alteromonadales目菌種分子親緣關係之探討

Abstract

本研究針對Alteromonadales目細菌的245種有效種標準株，以及屬於γ-Proteobacteria綱但分類地位尚未明確的22株之16S rRNA基因序列資料，利用親緣演化樹建構及識別核苷酸 (signature nucleotides) 分析為主，輔以傳統生理、生化特性分類方法，重新審視Alteromonadales目內各菌種間的分類關係。 本研究以鄰位連接法(neighbor-joining method)、最大似然法(maximum likelihood method)、最大簡約法(maximum parsimony method)三種演算法(前兩法均配合Jukes-Cantor (JC)和Kimura Two-Parameter (K2P)兩種Model)，進行五種親緣演化樹的建構，建構的演化樹皆可得到一個穩定的Alteromonadales cluster，其中可分為十七個subcluster， 根據分析結果建議在Alteromonadales目中增設八科，並建議將Alteromonadaceae科中的Glaciecola lipolytica和Aestuariibacter litoralis重新分類為同一新屬之兩種。Idiomarinaceae科中的Idiomarina則建議重新分成Idiomarina及Pseudidiomarina兩屬。

The 16S rRNA gene sequences of 245 type strains of Alteromonadales species and those of 22 strains belonging to unclassified group in the class γ-Proteobacteria have been collected in this study. To establish the effective phylogenetic relationship of these Alteromonadales strains, phylogenetic and signature nucleotide analyses, together with physiological and biochemical characterizations were conducted. Three algorithms, neighbor-joining method, maximum likelihood method and maximum parsimony method, were used to construct phylogenetic trees; the first two algorithms were incorporated in two models, Jukes-Cantor (JC) and Kimura Two-Parameter (K2P). All phylogenetic trees formed a stable Alteromonadales cluster that was divided into seventeen subclusters . The results indicated that eight new families might be established in the Alteromonadales. Moreover, Glaciecola lipolytica and Aestuariibacter litoralis could be reclassified as two different species in a novel genus . Our results also suggest that Pseudidiomarina is better retrieved and separated from the genus Idiomarina of the family Idiomarinaceae .