Free full text ruminococcus albus research literature

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1. Nitrogen utilization and metabolism in Ruminococcus albus 8

Abstract:

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The model rumen Firmicutes organism Ruminococcus albus 8 was grown using ammonia, urea, or peptides as the sole nitrogen source; growth was not observed with amino acids as the sole nitrogen source. Growth of R. albus 8 on ammonia and urea showed the same growth rate (0.08 h(-1)) and similar maximum cell densities (for ammonia, the optical density at 600 nm [OD600] was 1.01; and for urea, the OD600 was 0.99); however, growth on peptides resulted in a nearly identical growth rate (0.09 h(-1)) and a lower maximum cell density (OD600 = 0.58). To identify differences in gene expression and enzyme activities, the transcript abundances of 10 different genes involved in nitrogen metabolism and specific enzyme activities were analyzed by harvesting mRNA and crude protein from cells at the mid- and late exponential phases of growth on the different N sources. Transcript abundances and enzyme activities varied according to nitrogen source, ammoniaconcentration, and growth phase. Growth of R. albus 8 on ammonia and urea was similar, with the only observed difference being an increase in urease transcript abundance and enzyme activity in urea-grown cultures. Growth of R. albus 8 on peptides showed a different nitrogen metabolism pattern, with higher gene transcript abundance levels of gdhA, glnA, gltB, amtB, glnK, and ureC, as well as higher activities of glutamate dehydrogenase and urease. These results demonstrate that ammonia, urea, and peptides can all serve as nitrogen sources for R. albus and that nitrogen metabolism genes and enzyme activities of R. albus 8 are regulated by nitrogen source and the level of ammonia in the growth medium.

Author: Kim JN; Henriksen ED; Cann IK; Mackie RI
Journal: Appl Environ Microbiol,2014/5;80(10):3095-102.
Publication type: Journal Article; Research Support, Non-U.S. Gov't
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2. Complete genome of the cellulolytic ruminal bacterium Ruminococcus albus7

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Ruminococcus albus 7 is a highly cellulolytic ruminal bacterium that is a member of the phylum Firmicutes. Here, we describe the complete genome of this microbe. This genome will be useful for rumen microbiology and cellulosome biology articles and in biofuel production, as one of its major fermentation products is ethanol.

Author: Suen G; Stevenson DM; Bruce DC; Chertkov O; Copeland A; Cheng JF; Detter C; Detter JC; Goodwin LA; Han CS; Hauser LJ; Ivanova NN; Kyrpides NC; Land ML; Lapidus A; Lucas S; Ovchinnikova G; Pitluck S; Tapia R; Woyke T; Boyum J; Mead D; Weimer PJ
Journal: J Bacteriol,2011/10;193(19):5574-5.
Publication type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.
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3. Studies of the extracellular glycocalyx of the anaerobic cellulolytic bacteriumRuminococcus albus 7

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Anaerobic cellulolytic bacteria are thought to adhere to cellulose via several mechanisms, including production of a glycocalyx containing extracellular polymeric substances (EPS). As the compositions and structures of these glycocalyces have not been elucidated, variable-pressure scanning electron microscopy (VP-SEM) and chemical analysis were used to characterize the glycocalyx of the ruminal bacterium Ruminococcus albus strain 7. VP-SEM revealed that growth of this strain was accompanied by the formation of thin cellular extensions that allowed the bacterium to adhere to cellulose, followed by formation of a ramifying network that interconnected individual cells to one another and to the unraveling cellulose microfibrils. Extraction of 48-h-old whole-culture pellets (bacterial cells plus glycocalyx [G] plus residual cellulose [C]) with 0.1 N NaOH released carbohydrate and protein in a ratio of 1:5. Boiling of the cellulose fermentation residue in a neutral detergentsolution removed almost all of the adherent cells and protein while retaining a residual network of adhering noncellular material. Trifluoroacetic acid hydrolysis of this residue (G plus C) released primarily glucose, along with substantial amounts of xylose and mannose, but only traces of galactose, the most abundant sugar in most characterized bacterial exopolysaccharides. Linkage analysis and characterization by nuclear magnetic resonance suggested that most of the glucosyl units were not present as partially degraded cellulose. Calculations suggested that the energy demand for synthesis of the nonprotein fraction of EPS by this organism represents only a small fraction (<4%) of the anabolic ATP expenditure of the bacterium.

Author: Weimer PJ; Price NP; Kroukamp O; Joubert LM; Wolfaardt GM; Van Zyl WH ournal: Appl Environ Microbiol,2006/12;72(12):7559-66.
Publication type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.
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4. Albusin B, a bacteriocin from the ruminal bacterium Ruminococcus albus 7 that inhibits growth of Ruminococcus flavefaciens

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An approximately 32-kDa protein (albusin B) that inhibited growth of Ruminococcus flavefaciens FD-1 was isolated from culture supernatants of Ruminococcus albus 7. Traditional cloning and gene-walking PCR techniques revealed an open reading frame (albB) encoding a protein with a predicted molecular mass of 32,168 Da. A BLAST search revealed two homologs of AlbB from the unfinished genome of R. albus 8 and moderate similarity to LlpA, a recently described 30-kDa bacteriocin from Pseudomonas sp. strain BW11M1.

Author: Chen J; Stevenson DM; Weimer PJ
Journal: Appl Environ Microbiol,2004/5;70(5):3167-70.
Publication type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.
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5. Functional analyses of multiple lichenin-degrading enzymes from the rumen bacterium Ruminococcus albus 8

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Ruminococcus albus 8 is a fibrolytic ruminal bacterium capable of utilization of various plant cell wall polysaccharides. A bioinformatic analysis of a partial genome sequence of R. albus revealed several putative enzymes likely to hydrolyze glucans, including lichenin, a mixed-linkage polysaccharide of glucose linked together in β-1,3 and β-1,4 glycosidic bonds. In the present study, we demonstrate the capacity of four glycoside hydrolases (GHs), derived from R. albus, to hydrolyze lichenin. Two of the genes encoded GH family 5 enzymes (Ra0453 and Ra2830), one gene encoded a GH family 16 enzyme (Ra0505), and the last gene encoded a GH family 3 enzyme (Ra1595). Each gene was expressed in Escherichia coli, and the recombinant protein was purified to near homogeneity. Upon screening on a wide range of substrates, Ra0453, Ra2830, and Ra0505 displayed different hydrolytic properties, as they released unique product profiles. The Ra1595 protein, predicted to function as a β-glucosidase, preferred cleavage of a nonreducing end glucose when linked by a β-1,3 glycosidic bond to the next glucose residue. The major product of Ra0505 hydrolysis of lichenin was predicted to be a glucotriose that was degraded only by Ra0453 to glucose and cellobiose. Most importantly, the four enzymes functioned synergistically to hydrolyze lichenin to glucose, cellobiose, and cellotriose. This lichenin-degrading enzyme mix should be of utility as an additive to feeds administered to monogastric animals, especially those high in fiber.

Author: Iakiviak M; Mackie RI; Cann IK
Journal: Appl Environ Microbiol,2011/11;77(21):7541-50.
Publication type: Journal Article; Research Support, Non-U.S. Gov't
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