THE PHYLOGENETIC-RELATIONSHIPS OF CHLOROBIUM-TEPIDUM AND CHLOROFLEXUS-AURANTIACUS BASED UPON THEIR RECA SEQUENCES

Using RecA as the phylogenetic marker, the relationships of the green sulfur bacterium Chlorobium tepidum and the green non-sulfur bacterium Chloroflexus aurantiacus to other eubacteria were investigated. The r ecA genes of the two organisms were cloned, and the resulting protein sequences aligned with 86 other eubacterial RecA sequences. Cb. tepidu m was placed as the nearest relative to the Cytophaga/Flexibacter/Bact eroides group, a relationship supported by results obtained with sever al phylogenetic markers. Cf. aurantiacus was placed near Chlamydia tra chomatis and the high-GC Gram-positives; however, this branching patte rn was not strongly supported statistically by bootstrap analyses. Pos sible reasons for this ambiguity are discussed. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V .