Eubacterium

If a phylogenetic comparison is made of the 16S-Iike rRNAs from an archae-bacterium Halobacterium volcanii), a eubacterium E. coli), and a eukaryote (the yeast Saccharomyces cerevisiae), a striking similarity in secondary structure emerges (Figure 12.40). Remarkably, these secondary structures are similar despite the fact that the nucleotide sequences of these rRNAs themselves exhibit a low degree of similarity. Apparently, evolution is acting at the level of rRNA secondary structure, not rRNA nucleotide sequence. Similar conserved folding patterns are seen for the 23S-Iike and 5S-Iike rRNAs that reside in the... 

FIGURE 12.40 Phylogenetic comparison of secondary structures of 16S-Uke rRNAs from (a) a eubacterium (E. coli), (b) an archaebacterium (H. volcanii), (c) a eukaryote S. cerevisiae, a yeast). 

Deoxy-L-galactose (L-fucose) is common, and has only been found as the a- or )3-pyranoside. The rare D-fucose has, however, been found both as a-pyranoside, in the LPS frorn Pseudomonas cepacia serotypes B and E, and as a-furanoside, in the cell-wall antigen from Eubacterium saburreum L 452 and the O-antigens from different strains of Psuedomonas syrin-gae The a-furanoside, as in 3, has a cis relationship between the aglycon and OH-2. The corresponding P form has not yet been found. 6-Deoxy-o-and -L-talose are components of the extracellular polysaccharides from some strains of Butyrivibrio fibrisolvens and of the LPS from some strains of E. coli respectively. 

Three 3-amino-3,6-dideoxyhexoses, having the d- and L gluco and D-ga-lacto configurations, have been found. The two D-sugars are not very common, but occur in some 0-antigens for example, those from E. coli 0114 (Ref. 60) and E. coli 02 (Ref 61), respectively. The D-galacto isomer has also been found in the cell-wall polysaccharide from Eubacterium saburreum strain L13.3-Amino-3,6-dideoxy-L-glucose has been found in the core part of the Aeromonas hydrophila chemotype 111 LPS. 

Braune A, M Giitschow, W Fngst, M Blaut (2001) Degradation of quercitin and luteolin by Eubacterium ramulus. Appl Environ Microbiol 67 558-5567. 

Haddock JD, JG Ferry (1989) Purification and properties of phloroglucinol reductase from Eubacterium oxidoreducens G-41. J Biol Chem 264 4423-4427. 

Haddock JD, JG Ferry (1993) Initial steps in the anaerobic degradation of 3,4,5-trihydroxybenzoate by Eubacterium oxidoreducens characterization of mutants and role of 1,2,3,5-tetrahydroxybenzene. J Bacterial 175 669-673. 

Graentzdoerffer A, D Rauh, A Pich, JR Andreesen (2003) Molecular and biochemical characterization of two tungsten-and selenium-containing formate dehydrogenases from Eubacterium acidamophilum that are associated with components of an iron-only hydogenase. Arch Microbiol 179 116-130. 

Juszczak A, S Aono, MWW Adams (1991) The extremely thermophilic eubacterium Thermotoga maritima, contains a novel iron-hydrogenase whose cellular activity is dependent upon tungsten. J Biol Chem 266 13834-13841. 

Svetlitchnyi V, C Peschel, G Acker, O Meyer (2001) Two membrane-associated NiFeS-carbon monoxide dehydrogenases from the anaerobic carbon-monoxide-utilizing eubacterium Carboxydothermus hydrogeno-formans. J Bacterial 183 5134-5144. 

Muller E, K Fahlbusch, R Walther, G Gottschalk (1981) Formation of WV-dimethylglycine, acetic acid and butyric acid from betaine by Eubacterium limosum. Appl Environ Microbiol 42 439-445. 

This has been examined quite extensively in the context of the intestinal metabolism of bile acids and a number of reactions that are otherwise quite unusual have been observed, most frequently in organisms belonging to the genera Eubacterium or Clostridium. Illustrative examples include the following ... 

Masuda N, H Oda, S Hirano, M Masuda, H Tanaka (1984) 7a-dehydroxylation of bile acids by resting cells of a Eubacterium lentum-like intestinal anaerobe, strain c-25. Appl Environ Microbiol AT. 735-739. 

Mott GE, AW Brinkley, CL Mersinger (1980) Biochemical characterization of cholesterol-reducing Eubacterium. Appl Environ Microbiol 40 1017-1022. 

Krumholz LR, RL Crawford, ME Hemling, MP Bryant (1987) Metabolism of gallate and phloroglucinol in Eubacterium oxidoreducens via 3-hydroxy-5-oxohexanoate. J Bacteriol 169 1886-1890. 

Beuscher HU, JR Andressen (1984) Eubacterium angustum sp. nov., a Gram-positive anaerobic, non-spore-forming, obligate purine fermenting organism. Arch Microbiol 140 2-8. 

Goodacre, R. Hiom, S. I Cheese man, S. L. Murdoch, D. Weightman, A. J. Wade, W. G. Identification and discrimination of oral asaccharolytic Eubacterium spp. using pyrolysis mass spectrometry and artificial neural networks. Curr. Microbiol. 1996,32,77-84. 

Lutnaes, B. F., A. Oren, and S. Liaaen-Jensen. 2002. New C-40 carotenoid acyl glycoside as principal carotenoid in Salinibacter ruber, an extremely halophilic eubacterium. J. Nat. Products 65 1340-1343. 

Yokoyama, A., G. Sandmann, T. Hoshino, K. Adachi, M. Sakai, and Y. Shizuri. 1995. Thermozeaxanthins, new carotenoid-glycoside-esters from thermophilic eubacterium Thermus thermophilus. Tetrahedron Lett. 36 4901 1904. 

The chicken intestinal microbiota is composed principally of Gram-positive bacteria (Gong et al., 2002). The lactobacilli are predominant in the small intestine (with smaller numbers of streptococci and enterobacteria), whereas the caecal flora is composed mainly of anaerobes and fewer numbers of facultative bacteria. Predominant cultured flora of the ileum of chicken include Lactobacillus, Streptococcus, E. coli and Eubacterium, while Eubacterium and Bacteroides dominated the caecum flora. 

Rifaximin has been shown to possess good antibacterial activity against a variety of anaerobic bacteria (table 3) [24, 27, 28], Anaerobes have been shown to be capable of producing ammonia (especially Clostridia), which has been incriminated in the pathogenesis of hepatic encephalopathy [29], The authors suggested that since rifaximin is a nonabsorbable and effective antibiotic against anaerobic flora, it would be an ideal treatment for patients with compromised hepatic function. Eubacterium is inhibited by rifaximin with an MIC90 < 2 pg/ml [27]. 

To understand the role of antibiotics, it is important to understand their effects on the fecal flora. The normal flora consists of a complex bacterial population with 400-500 distinct species of bacteria (table 2a). More than 99% of the total organisms are accounted for by non-sporeforming anaerobic rods [28] the four major species are Bacteroides, bifidobacteria, eubacteria and peptostrepto-cocci [29], Other common species are Escherichia coli, Streptococcus viridans, Streptococcus salivarius and lacto-bacilli. Mette et al. [30] clarified the prevalence of species in fecal flora by listing the four most common anaerobes Bacteroides spp., Eubacterium spp., Bifidobacterium spp. and anaerobic cocci) and three common aerobes E. coli spp., Enterococcus spp. and Lactobacillus spp.) (table 2b). 

Rafii F, Smith DB, Benson RW, Cemiglia CE (1992) Immunological homology among azoreductases from Clostridium and Eubacterium strains isolated from human intestinal microflora. J Basic Microbiol 32 99-105... 

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