Identification of phototrophic sulfur bacteria through the analysis of lmwRNA band patterns

Several phototrophic sulfur bacteria were identified preliminarily through the analysis of the low-molecular-weight RNA fraction (lmwRNA) of bacterial cells. This fraction includes the ribosomal 5S RNA and several transfer RNAs. These molecules were separated by high-resolution electrophoresis in polyacrylamide gels, and the resulting band patterns were used as fingerprints for the identification of the organisms. We examined a large number of well-characterized reference strains together with a broad range of purple sulfur bacterial isolates from freshwater and marine environments. A cluster analysis was run using the similarity matrix calculated from the band patterns. Despite the shortcomings of the method, close relatives were clustered together yielding a number of groups consistent with the phylogenetic arrangement established through the analyses of a few available 16S rRNA gene sequences. Thus, the classification obtained gives further support to rearrangement of the group as the analyses of 16S rRNA gene sequences had previously suggested. We conclude that the analysis of lmwRNA band patterns is a rapid and simple tool for grouping and preliminarily identifying new isolates of phototrophic sulfur bacteria.