Metabolic Activities of the Normal Colonic Flora

Macfarlane, G.T.; Gibson, Glenn R.

doi:10.1007/978-1-4471-3443-5_2

Cited by 64 publications

(39 citation statements)

References 167 publications

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“…The 14 bacterial species chosen represent different microbial communities occupying diverse nutritional niches within the intestinal microbiota. These defined bacterial communities included two groups of saccharolytic anaerobes: bacteria belonging to the genera Bifidobacterium and Bacteroides, which play important roles in the catabolism of complex polymers in the large bowel (27). Bifidobacteria and bacteroides are numerically significant in the colon, typically occurring in excess of 10 11 per gram of intestinal contents (28).…”

Section: Discussionmentioning

confidence: 99%

Effects of Antibiotics on Bacterial Species Composition and Metabolic Activities in Chemostats Containing Defined Populations of Human Gut Microorganisms

Newton

Macfarlane

2013

Antimicrob Agents Chemother

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The composition and metabolic activities of the human colonic microbiota are modulated by a number of external factors, including diet and antibiotic therapy. Changes in the structure and metabolism of the gut microbiota may have long-term consequences for host health. The large intestine harbors a complex microbial ecosystem comprising several hundreds of different bacterial species, which complicates investigations on intestinal physiology and ecology. To facilitate such studies, a highly simplified microbiota consisting of 14 anaerobic and facultatively anaerobic organisms (Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bifidobacterium longum, Bifidobacterium infantis, Bifidobacterium pseudolongum, Bifidobacterium adolescentis, Clostridium butyricum, C. perfringens, C. bifermentans, C. innocuum, Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Lactobacillus acidophilus) was used in this investigation. Ampicillin [9.2 g (ml culture) ؊1 ] was added to two chemostats operated at different dilution rates (D; 0.10 h ؊1 and 0.21 h ؊1 ), and metronidazole [76.9 g (ml culture) ؊1 ] was added to a third vessel (D ‫؍‬ 0.21 h ؊1 ). Perturbations in bacterial physiology and metabolism were sampled over a 48-h period. Lactobacillus acidophilus and C. bifermentans populations did not establish in the fermentors under the imposed growth conditions. Ampicillin resulted in substantial reductions in bacteroides and C. perfringens populations at both dilution rates. Metronidazole strongly affected bacteroides communities but had no effect on bifidobacterial communities. The bacteriostatic effect of ampicillin on bifidobacterial species was growth rate dependent. Several metabolic activities were affected by antibiotic addition, including fermentation product formation and enzyme synthesis. The growth of antibiotic-resistant bifidobacteria in the large bowel may enable them to occupy ecological niches left vacant after antibiotic administration, preventing colonization by pathogenic species.

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Section: Discussionmentioning

confidence: 99%

Effects of Antibiotics on Bacterial Species Composition and Metabolic Activities in Chemostats Containing Defined Populations of Human Gut Microorganisms

Newton

Macfarlane

2013

Antimicrob Agents Chemother

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“…Our work provides independent support for this explanation as well as an alternative way of producing recombinant sulfatase. The Prevotella sulfatase mdsA is not expressed in E. coli but is expressed in the alternative Bacteroides expression system, which is known to contain chuR, Mucin is thought to provide one of several endogenous energy sources for colon bacteria (12), and there is accumulating evidence that heavy sulfation of mucin rate-limits its breakdown. Clearly, it is important to identify specific sulfatases from bacteria that remove sulfate from these sulfated mucin sugars and how the levels of these sulfatases are regulated.…”

Section: Discussionmentioning

confidence: 99%

Cloning of a Mucin-Desulfating Sulfatase Gene from Prevotella Strain RS2 and Its Expression Using a Bacteroides Recombinant System

et al. 2000

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A gene encoding the mucin-desulfating sulfatase in Prevotella strain RS2 has been cloned, sequenced, and expressed in an active form. A 600-bp PCR product generated using primers designed from amino acid sequence data was used to isolate a 5,058-bp genomic DNA fragment containing the mucin-desulfating sulfatase gene. A 1,551-bp open reading frame encoding the sulfatase proprotein was identified, and the deduced 517-amino-acid protein minus its signal sequence corresponded well with the published mass of 58 kDa estimated by denaturing gel electrophoresis. The sulfatase sequence showed homology to aryl-and nonarylsulfatases with different substrate specificities from the sulfatases of other organisms. No sulfatase activity could be detected when the sulfatase gene was cloned into Escherichia coli expression vectors. However, cloning the gene into a Bacteroides expression vector did produce active sulfatase. This is the first mucin-desulfating sulfatase to be sequenced and expressed. A second open reading frame (1,257 bp) was identified immediately upstream from the sulfatase gene, coding in the opposite direction. Its sequence has close homology to iron-sulfur proteins that posttranslationally modify other sulfatases. By analogy, this protein is predicted to catalyze the modification of a serine group to a formylglycine group at the active center of the mucin-desulfating sulfatase, which is necessary for enzymatic activity.Mucins are high-molecular-weight glycoproteins which form the structural component of the protective mucus gel layer at the surfaces of the gastrointestinal, respiratory, and female genital tracts. Colonic mucin, particularly in the proximal region, contains significant levels of sulfate covalently bound to the mucin oligosaccharide chains, and levels of 2.0 to 6.5 g of sulfate per 100 g of mucin have been found (9, 17). Heavily sulfated mucins (sulfomucins) have many of the general lubricating and barrier functions of mucins with lower sulfate levels. There is accumulating evidence that sulfomucins may, in addition, rate-limit mucin degradation by mucin-degrading bacterial enzymes (4,7,13,15,18,24,26,27), and this role is thought to be particularly important in the colon, where approximately 10 14 bacterial cells are located (10). There have been reports of mucin-desulfating sulfatases that partially remove the sulfate from sulfomucin in a number of bacteria from the mouth, stomach, and colon and in feces. The effect of such sulfatases is to increase the susceptibility of the mucin to degradation by other mucin-degrading enzymes (4, 27). Elevated levels of bacterial mucin-desulfating sulfatases are found in feces of patients with ulcerative colitis (26). The sulfated sugar specificity of these fecal sulfatases, the number of different types present, the bacterial origin of the elevated levels, and the conditions which regulate bacterial production of such enzymes are unknown. The types of mucin-desulfating sulfatases that might be predicted include sulfatases specific for galactose-3-sulfate, g...

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“…Most of the data available on the gut bacteria have been generated by cultivation and enumeration (29). Though selective growth media and special growth conditions have been developed to culture intestinal bacteria, in complex bacterial communities only a small part, 10% to 40%, of the flora is covered (18,22,36). The 16S ribosomal DNA (rDNA) is a suitable marker gene for taxonomic and phylogenetic applications (1,8,20,30,37,38).…”

mentioning

confidence: 99%

Quantification of Intestinal Bacterial Populations by Real-Time PCR with a Universal Primer Set and Minor Groove Binder Probes: a Global Approach to the Enteric Flora

Ott¹,

Musfeldt²,

Ullmann

et al. 2004

J Clin Microbiol

127

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Metabolic Activities of the Normal Colonic Flora

Cited by 64 publications

References 167 publications

Effects of Antibiotics on Bacterial Species Composition and Metabolic Activities in Chemostats Containing Defined Populations of Human Gut Microorganisms

Effects of Antibiotics on Bacterial Species Composition and Metabolic Activities in Chemostats Containing Defined Populations of Human Gut Microorganisms

Cloning of a Mucin-Desulfating Sulfatase Gene from Prevotella Strain RS2 and Its Expression Using a Bacteroides Recombinant System

Quantification of Intestinal Bacterial Populations by Real-Time PCR with a Universal Primer Set and Minor Groove Binder Probes: a Global Approach to the Enteric Flora

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