Inferring Eubacterial Phylogeny from SS Ribosomal RNA Structure Analysis

Abstract

Based on analysis of 165 ribosomal RNA oligonucleotide catalogs of about 400 eubacterial species Woese et al. (1985) made a proposal to divide the eubacterial primary kingdom into 10 major phyla. Two years later with over 500 species characterized and with more than 50 nearly complete sequences, the earlier conclusions were significantly refined and extended (Woese, 1967). The picture obtained is substantially different from the classification system based on morphological and metabolic data In the 8th edition of Bergey’s Manual (Buchanan and Gibbons, 1974). Investigation of another universally occurring molecule such as 55 ribosomal RNA ought to help clarify this matter. So far about 160 eubacterial 55 RNA sequences have been published, but the distribution over the 10 major phyla is very uneven as can be seen from Table 1. For example, in the phylum of purple bacteria and relatives almost 80 species have been examined, whereas in the phylum of green sulfur bacteria, along with 4 other major phyla, no representatives whatsoever have been investigated. It is our aim to Lessen these gaps, in order to make possible a comparison with the view based on 165 ribosomal RNA. Rt present, progress has been made for several phyla, while work has started on others (Table 1). In this paper we present a tree derived from the weighted pairwise grouping of over 180 eubacterial 55 RNA sequences including several sequences of formerly undocumented phyla.