Phylogenetic analysis of Formivibrio citricus, Propionivibrio dicarboxylicus, Anaerobiospirillum thomasii, Succinimonas amylolytica and Succinivibriodextrinosolvens and proposal of Succinivibrionaceae fam. nov.

The phylogenetic position of Gram-negative, strictly anaerobic, non-spore-f orming bacteria, representing four different genera, was determined by anal ysis of their 16S rDNA sequences. Formivibrio citricus and Propionivibrio d icarboxylicus are members of the beta-subclass of the class Proteobacteria. While Formivibrio citricus stands phylogenetically isolated, Propionivibri o dicarboxylicus is moderately related to members of the genus Rhodocyclus. Succinimonas amylolytica and Succinivibrio dextrinosolvens are members of the gamma-subclass of the class Proteobacteria in which they, together with members of the genus Anaerobiospirillum and Ruminokacter amylophilus, form a separate line of descent. This phylogenetic group is described as Succin ivibrionaceae fam. nov.