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THE EUBACTERIA
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PHYLUM ANOXYBACTERIA

INTRODUCTION TO THE ANOXYBACTERIA

The Anoxybacteria are rods and cocci that utilize anaerobic fermentation, but some are capable of tolerating some ambient oxygen.  They have very limited synthetic abilities, ferment a wide array of organic compounds.  They are economically important as parasites (e.g. botulism and tetanus; Figure A) and as important mutualistic symbioses in animals that ferment their foods.  Indeed, they are found as non-pathogenic members of the intestinal floras of animals in general.  Some are nitrogen-fixers.  

clostridium-arizona.jpg (31569 bytes)

A. Clostridium showing the characteristic Gram-positive response.
Image taken from: http://ag.arizona.edu/pubs/general/resrpt1998/25.jpg

SYNOPTIC DESCRIPTION OF THE ANOXYBACTERIA

The following description comes mainly from Margulis and Schwartz (1998), Barnes (1984), Brock et al. (1994), and Tudge (2000).

I. SYNONYMS: Fermenting bacteria, anaerobic Gram-positive bacteria.

II. PHYLUM CHARACTERISTICS:

A. Structure

Cell Form: Variable; rods or cocci.

Cell Wall: Gram+.

Motility: Non-motile or motile.

B. Physiology

O2 Tolerance: Obligate anaerobes.

Substrates: Quite variable, they can ferment a wide variety of organic compounds.

Products: Fermentation products are quite varied; usually, they produce small organic acids, ethanol, CO2, NH3, and sometimes H2. Organisms like Clostridium (Figure A) release very powerful toxins.

C. Other: They do not tolerate oxygen; they are unable to synthesize porphyrins.

D. Ecology: Free-living in anaerobic soils and aquatic sediments, some parasites.

SYSTEMATICS OF THE ANOXYBACTERIA

This is a modification of Barnes (1984) and Margulis and Schwartz (1988) in which the phylum is designated M-14.   Margulis and Schwartz (1998) lumped these taxa together with the Aerendosporobacteria as the Phylum Endospora (B-10).  I have chosen to retain the separation and regard the taxon Endospora as a superphylum.  Bergey's Manual of Systematic Bacteriology, volume 2, sections 12, 13 and 14 (Holt, 1986) describe the taxa which I include in the Anoxybacteria. Section 12 (The Gram-Positive Cocci). Section 13 (Endospore-forming Gram-Positive Rods and Cocci, in part) includes taxa which I place in the Class Clostridiatia.   Bergey's Manual of Systematic Bacteriology, 2nd edition (Garrity et al. 2001) treats the taxa that I include in the Anoxybacteria as a class ("Clostridia") of phylum Firmicutes (BXIII).

HIERARCHICAL CLASSIFICATION OF THE ANOXYBACTERIA

I have used the general organization of the group called "Clostridia" in Garrity et al. (2001 and 2003).  I have raised the taxa to be commensurate with a phylum-level organization as suggested by Margulis and Schwartz (1998).

CLASS CLOSTRIDIAE

ORDER CLOSTRIDIALES

Clostridium, Acetivibrio, Acidaminobacter, Anaerobacter, Arthromitus, Caloramator, Coprobacillus, Natronincola, Oxobacter, Sarcina, Sporobacter, Thermobachium, Thermohalobacter, Tindallia.

ORDER LACHNOSPIRALES

Lachnospira, Acetitomaculum, Anaerofilum, Butyrivibrio, Catenibacterium, Catonella, Coprococcus, Johnsonella, Pseudobutyrvibrio, Roseburia, Ruminococcus, Sporobacterium.

ORDER PEPTOSTREPTOCOCCALES

Peptostreptococcus, Filifactor, Finegoldia, Fusibacter, Helcococcus, Micromonas, Tissierella.

ORDER EUBACTERIALES

Eubacterium, Acetobacterium, Anaerovorax, Mogibacterium, Pseudoramibacter.

ORDER PEPTOCOCCALES

Peptococcus, Anaeroarcus, Anaerosinus, Anaerovibrio, Carboxydothermus, Centipeda, Dehalobacter, Dendrosporobacter, Desulfitobacterium, Desulfonispora, Desulfosporosinus, Desulfotomaculum, Mitsuokella, Propioispira, Succinispira, Syntrophobotulus, Thermoterrabacterium.

ORDER HELIOBACTERIALES

Heliobacterium, Heliobacillus, Heliophilum, Heliorestis.

ORDER ACIDAMINOCOCCALES

Acidaminococcus, Acetonema, Anaeromusa, Dialister, Megasphaera, Papillibacter, Pectinatus, Phascolarctobacterium, Quinella, Schwartzia, Selenomonas, Sporomusa, Succiniclasticum, Veillonella, Zymophilus.

ORDER SYNTROPHOMONADALES

Syntrophomonas, Acetogenium, Aminobacterium, Aminomonas, Anaerobaculum, Anaerobrancha, Caldicellulostruptor, Dethiosulfovibrio, Pelospora, Syntrophospora, Syntrophothermus, Thermaerobacter, Thermanaerobacter, Thermanaerovibrio, Thermohydrogenium, Thermosyntropha.

CLASS THERMOANDEROBACTERIAE

ORDER THERMOANDEROBACTERIALES

Thermoanderobacterium, Ammonifex, Carboxydobrachium, Coprothermobacter, Moorella, Sporomaculum, Thermacetogenium, Thermoanaerobacter, Theremoanaerobium.

CLASS HALOANDEROBIAE

ORDER HALOANDEROBIALES

Haloanderobium, Halocella, Halothermothrix, Natroniella.

ORDER HALOBACTERALES

Halobacteroides, Acetohalobium, Haloanaerobacter, Orenia, Sporohalobacter.

This page is maintained by Jack R. Holt. Last revised: 03/17/2008.