CURRENTMICROBIOLOGY, Vol. 7 (1982), pp. 127-132 Current Microbiology An International Journal A Phylogenetic Analysis of Anaerobic Eubacteria Capable of Synthesizing Acetate from Carbon Dioxide Ralph S. Tanner,? Erko Stackebrandt,$ George E. Fox,w Ramesh Gupta,]l Linda J. Magrum,I] and Carl R. Woesell* t Department of Microbiology, University of Illinois, Urbana, Illinois 61801, USA ~;Department of Microbiology, Technische Universitfit M0nchen, Arcisstrasse 21, D-8000 Mfinchen 2, Federal Republic of Germany w Department of Biophysical Sciences, University of Houston, Houston, Texas 77004, USA I[Department of Genetics and Development, University of Illinois, Urbana, illinois 61801, USA Abstract. Acetobacterium woodii, Acetogenium kivui, CIostridium aceticum, C. acidiurici, C. cylindrosporum, C. formicoaceticum, C. thermoaceticum, Eubacterium limosum, and Pepto- coccus glycinophilus were characterized by oligonucleotide cataloging of their 16S ribosomal RNA to determine whether the ability to synthesize acetate from CO2 is a phylogenetic trait. The ability to synthesize acetate from CO2 apparently is not a valid phylogenetic marker. The Eubacterium and Peptococcus species examined here are less related to other species in their genera than they are to different species of CIostridium. The Eubacterium species examined here show little relatedness to the genus Propionibacterium. The acetogenic eubacteria belong to the phylogenetic group defined basically by the Gram-positive sporeforming anaerobes. A group of bacteria capable of reducing CO 2 to acetate was listed in a 1969 review on the produc- tion of acetate from CO2 by heterotrophs [9]: Clos- tridium acidiurici, C. cylindrosporum, Peptococcus glycinophilus, Eubacterium limosum (Butyribacter- ium rettgeri), C. aceticum, C. formicoaceticum (Clostridium strain A1), and C. thermoaceticum. Clostridium aceticum, which was recently recov- ered [3], can also use H2 to reduce CO2 to acetate. Two nonsporeforming bacteria able to form acetate from H2 and CO2, Acetobacterium woodii [2] and Acetogenium kivui [7], have been isolated since the aforementioned review [9] appeared. Recently, Eu- bacterium limosum has been shown capable of using H2 to reduce CO2 to acetate [12]. In this study, we decided to use oligonucleotide cataloging of ribosomal RNA (rRNA) to determine whether the ability to synthesize acetate from CO2 can be considered a phylogenetic trait. The methanogens, which synthesize CH4 from CO2, have been shown to form a phylogenetically related group by compar- ative cataloging of 16S rRNA [1]. In a previous publication, Acetobacterium woodii and Eubacterium limosum were shown to be * To whom reprint requests should be addressed. related to each other, and both are related to Clostridium barkeri [14]. The association between anaerobic eubacteria capable of producing acetate from COz and other clostridia will be discussed here. Johnson and Francis defined several groups in the genus Clostridium by 23S rRNA homology [6]. Clostridium butyricum, C. scatologenes, and C. pasteurianum are members of homology group I, a low mol% G+C cluster. Clostridium lituseburense is the type species of homology group I1, another low mol% G+C cluster. Clostridium aminovaleri- cum is a species with a low tool% G+C in its DNA and is not a member of either of these [6] homology groups. Clostridium barkeri, whose DNA has a higher tool% G+C, is not a member of either 23S rRNA homology groups. These species were select- ed to represent the clostridia in our study. The relationship between the genera Eubacterium and Propionibacterium also will be discussed. Materials and Methods Clostridium acidiurici ATCC 7906, C. aminovalericum ATCC 13725, C. cylindrosporum ATCC 7905, C. formicoaceticum ATCC 0343-8651/82/0007-0127 $01.20 9 1982 Springer-Verlag New York Inc.