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Trichothecenes
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
I. Malbrán, C.A. Mourelos, J.R. Girotti, G.A. Lori
However, the isolation of pure cultures from animal guts with the capacity to detoxify DON has been hindered by the strictly anaerobic nature of these bacteria and their fastidious nutritional demands.19Eubacterium sp. BBSH 797, isolated from the rumen of a cow, was the first pure culture capable of de-epoxidizing both type A and type B trichothecenes in vitro under anaerobic conditions.110–112 The ability of Eubacterium sp. BBSH 797 to counteract the toxicity of DON in commercial broilers at the gut level has also been reported,113 and a commercial feed additive product based on this strain is available.
Josamycin and Rosaramicin
Published in M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson, Kucers’ The Use of Antibiotics, 2017
Of the Gram-positive anaerobes, Peptococcus, Peptostreptococcus, Propionibacterium, and Eubacterium spp. are susceptible to josamycin, but Clostridium spp. strains may be resistant (Long et al., 1976). Rosaramicin is also active against anaerobes (Sutter and Finegold, 1976). It is much more active than erythromycin against Peptococcus spp., but has the same activity as erythromycin against the others, such as Peptostreptococcus spp., Eubacterium spp., Propionibacterium spp., Actinomyces spp., and Lactobacillus spp. Clostridium tetani and C. perfringens are susceptible to spiramycin and rosaramicin.
Pharmacological Activity of Saikosaponins
Published in Sheng-Li Pan, Bupleurum Species, 2006
Saikosaponin-a, -d, and -e series are disaccharide glycosides containing the 3-O-β-d-glucopyranosyl (1 → 3) β-d-fucopyranosyl moiety (Nose et al., 1989). Saikosaponins-a and -d, characterized by an ether linkage between C13 and C28, are epimers at C16 with β-OH and α-OH group, respectively. Saikosaponin-c is a trisaccharide glycoside with a methyl group at C23. Meanwhile, saikosaponin-b1 and -b2 with a carbinol function at C28 are epimers at C16 with a β-OH and α-OH group, respectively. Saikosaponin-e is characterized by the presence of fucosylpyranosylglucopyranosyl moiety at C3, β-OH at C16, and a methyl group at C4. Metabolism of saikosaponins is expected to follow the general metabolic pathway for saponins. Under gastric condition (Shimizu et al., 1985; Nose et al., 1989), saikosaponin-a and saikosaponin-d are transformed to saikosaponin-b1 and saikosaponin-b2, respectively. Further, saikosaponin a yields saikosaponin-g, which possesses a homoannular diene moiety at C9 (11), 12 under the same acidic condition. In intestinal contents, saikosaponins are converted to corresponding prosaikogenins, containing one sugar, by the cleavage of β-d-glucopyranosyl-β-d-fucopyranosyl moiety due to the existence of intestinal microflora, and in turn, each prosaikogenin is converted to the corresponding saikogenin, an aglycone of saikosaponin. From human intestinal bacterium, Eubacterium sp. A-44, two glycosidases, capable of hydrolyzing saikosaponins to saikogenins, were isolated and characterized as saikosaponin-hydrolyzing β-d-glucosidase and prosaikogenin-hydrolyzing β-d-fucosidase (Shimizu et al., 1985; Kida et al., 1998).
The high prevalence of Clostridioides difficile among nursing home elders associates with a dysbiotic microbiome
Published in Gut Microbes, 2021
John P. Haran, Doyle V. Ward, Shakti K. Bhattarai, Ethan Loew, Protiva Dutta, Amanda Higgins, Beth A. McCormick, Vanni Bucci
Here we are reporting on the association of lower risk for C. difficile colonization among nursing home elders taking a PPI daily and propose that a possible mechanism lies in the differences in microbiome composition between users and non-users of PPIs. Among non-colonized elders taking a PPI, we noticed enrichment in gut bacteria such as Eubacterium species and Faecalibacterium prausnitzii. The Eubacterium spp. are an important butyrate-producing bacterial species which contributes to the maintenance of the gut barrier functions, and has both immunomodulatory and anti-inflammatory properties.29Faecalibacterium prausnitzii, one of the most abundant and important butyrate commensal bacteria of the human gut microbiota,69,70 also show enrichment in non-colonized PPI users. The subset of species displaying a greater abundance in PPI-treated elders without C. difficile compared to PPI-untreated and whose abundance was decreasing with increasing C. difficile prevalence included species five (C. symbiosum, D. longicatena, E. eligens, E. rectale and F. prausnitzii) belong to the Clostridiales order. These species have also been associated with protection against inflammatory and infectious conditions in both mice and humans, including C. difficile infection.71–73 Vincent et al. (2013) found that Eubacteria and Faecalibacterium are depleted in CDI patients.73 It additionally reported a decrease in the family Bacteroidaceae, which is consistent with our analysis finding B. uniformis enriched in PPI with no CD and reduced with higher prevalence of C. difficile, an association noted by others.74–76 Our findings suggest that changes in the intestinal microbiome among elders exposed to a PPI may be associated with a less favorable environment for C. difficile colonization.
Gut microbes from the phylogenetically diverse genus Eubacterium and their various contributions to gut health
Published in Gut Microbes, 2020
Arghya Mukherjee, Cathy Lordan, R. Paul Ross, Paul D. Cotter
Bile acids (BA) are host-produced metabolites derived from cholesterol in liver pericentral hepatocytes. Cholic acid (CA) and chenodeoxycholic acid (CDCA) are the primary BAs produced in liver which are then conjugated to taurine or glycine before being temporarily stored in the gallbladder; these BAs subsequently undergo postprandial secretion to reach the gut. 95% of the total BA pool in the gut are absorbed efficiently and recycled back to the liver via the portal vein; this cyclic process is known as enterohepatic circulation. The rest serves as a substrate for bacterial metabolism in the gut and constitutes a critical route for cholesterol excretion from the body. BAs can occur in several forms including primary BA, secondary BA, conjugated, or unconjugated. Various members of the gut microbiota are capable of transforming BAs, thereby influencing the composition of the local BA pool along with various other aspects of host physiology. Gut microbes including Eubacterium spp. that possess the enzyme bile salt hydrolase (BSH) are able to hydrolyze the C-24 N-acyl amide bond in conjugated BAs to release glycine/taurine moieties121 (Figure 4). Indeed, Eubacterium spp. along with other genera such as Roseburia and Clostridium constitute a major reservoir of BSHs in the gut.172 Deconjugation increases the pKa of BAs to ~5, thereby making them less soluble which in turn leads to inefficient absorption and replenishment of the lost BA by de novo synthesis from cholesterol.173 Additionally, BSH activity can disrupt micelle formation and absorption, resulting in a significant reduction of cholesterol levels.159 Being reasonably widely distributed in the gut microbiota, BSH activity can thus be modulated to regulate weight gain and cholesterol levels in the host. Deconjugation also helps in bile detoxification through recapture and export of cotransported protons by the free BAs generated, thereby negating the pH.174 Another way intestinal bacteria can transform BAs is through the oxidation and epimerization of hydroxyl groups at C3, C7, and C12 positions, resulting in the generation of isobile (β-hydroxy) salts.175 Epimerization involves the reversible stereochemical change from α to β configuration and vice versa, generating a stable oxo-bile acid intermediate. This process is catalyzed by α- and β-hydroxysteroid dehydrogenases (HSDHs) and can be carried out by a single bacterial species containing both enzymes or through proto-cooperation between two species, with each contributing one enzyme. HSDH activity has been reported in several species including Eubacterium spp.176