This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Walker, A. W.
Right arrow Articles by Flint, H. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Walker, A. W.
Right arrow Articles by Flint, H. J.
Agricola
Right arrow Articles by Walker, A. W.
Right arrow Articles by Flint, H. J.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, July 2005, p. 3692-3700, Vol. 71, No. 7
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.7.3692-3700.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

pH and Peptide Supply Can Radically Alter Bacterial Populations and Short-Chain Fatty Acid Ratios within Microbial Communities from the Human Colon

Alan W. Walker,1 Sylvia H. Duncan,1 E. Carol McWilliam Leitch,1 Matthew W. Child,2 and Harry J. Flint1*

Microbial Genetics Group, Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen, United Kingdom,1 Microbiology and Gut Biology Group, University of Dundee, Dundee, United Kingdom2

Received 23 November 2004/ Accepted 31 January 2005

The effects of changes in the gut environment upon the human colonic microbiota are poorly understood. The response of human fecal microbial communities from two donors to alterations in pH (5.5 or 6.5) and peptides (0.6 or 0.1%) was studied here in anaerobic continuous cultures supplied with a mixed carbohydrate source. Final butyrate concentrations were markedly higher at pH 5.5 (0.6% peptide mean, 24.9 mM; 0.1% peptide mean, 13.8 mM) than at pH 6.5 (0.6% peptide mean, 5.3 mM; 0.1% peptide mean, 7.6 mM). At pH 5.5 and 0.6% peptide input, a high butyrate production coincided with decreasing acetate concentrations. The highest propionate concentrations (mean, 20.6 mM) occurred at pH 6.5 and 0.6% peptide input. In parallel, major bacterial groups were monitored by using fluorescence in situ hybridization with a panel of specific 16S rRNA probes. Bacteroides levels increased from ca. 20 to 75% of total eubacteria after a shift from pH 5.5 to 6.5, at 0.6% peptide, coinciding with high propionate formation. Conversely, populations of the butyrate-producing Roseburia group were highest (11 to 19%) at pH 5.5 but fell at pH 6.5, a finding that correlates with butyrate formation. When tested in batch culture, three Bacteroides species grew well at pH 6.7 but poorly at pH 5.5, which is consistent with the behavior observed for the mixed community. Two Roseburia isolates grew equally well at pH 6.7 and 5.5. These findings suggest that a lowering of pH resulting from substrate fermentation in the colon may boost butyrate production and populations of butyrate-producing bacteria, while at the same time curtailing the growth of Bacteroides spp.

* Corresponding author. Mailing address: Microbial Genetics Group, Rowett Research Institute, Greenburn Rd., Bucksburn, Aberdeen AB21 9SB, United Kingdom. Phone: (44) 1224-716651. Fax: 1224-716687. E-mail: hjf{at}rri.sari.ac.uk.

Applied and Environmental Microbiology, July 2005, p. 3692-3700, Vol. 71, No. 7
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.7.3692-3700.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Salazar, N., Gueimonde, M., Hernandez-Barranco, A. M., Ruas-Madiedo, P., de los Reyes-Gavilan, C. G. (2008). Exopolysaccharides Produced by Intestinal Bifidobacterium Strains Act as Fermentable Substrates for Human Intestinal Bacteria. Appl. Environ. Microbiol. 74: 4737-4745 [Abstract] [Full Text]  
  • Belenguer, A., Duncan, S. H., Holtrop, G., Anderson, S. E., Lobley, G. E., Flint, H. J. (2007). Impact of pH on Lactate Formation and Utilization by Human Fecal Microbial Communities. Appl. Environ. Microbiol. 73: 6526-6533 [Abstract] [Full Text]  
  • Louis, P., Flint, H. J. (2007). Development of a Semiquantitative Degenerate Real-Time PCR-Based Assay for Estimation of Numbers of Butyryl-Coenzyme A (CoA) CoA Transferase Genes in Complex Bacterial Samples. Appl. Environ. Microbiol. 73: 2009-2012 [Abstract] [Full Text]  
  • Duncan, S. H., Belenguer, A., Holtrop, G., Johnstone, A. M., Flint, H. J., Lobley, G. E. (2007). Reduced Dietary Intake of Carbohydrates by Obese Subjects Results in Decreased Concentrations of Butyrate and Butyrate-Producing Bacteria in Feces. Appl. Environ. Microbiol. 73: 1073-1078 [Abstract] [Full Text]  
  • Grider, J. R., Piland, B. E. (2007). The peristaltic reflex induced by short-chain fatty acids is mediated by sequential release of 5-HT and neuronal CGRP but not BDNF. Am. J. Physiol. Gastrointest. Liver Physiol. 292: G429-G437 [Abstract] [Full Text]  
  • Ramsay, A. G., Scott, K. P., Martin, J. C., Rincon, M. T., Flint, H. J. (2006). Cell-associated {alpha}-amylases of butyrate-producing Firmicute bacteria from the human colon.. Microbiology 152: 3281-3290 [Abstract] [Full Text]  
  • Aminov, R. I., Walker, A. W., Duncan, S. H., Harmsen, H. J. M., Welling, G. W., Flint, H. J. (2006). Molecular Diversity, Cultivation, and Improved Detection by Fluorescent In Situ Hybridization of a Dominant Group of Human Gut Bacteria Related to Roseburia spp. or Eubacterium rectale. Appl. Environ. Microbiol. 72: 6371-6376 [Abstract] [Full Text]  
  • Scott, K. P., Martin, J. C., Campbell, G., Mayer, C.-D., Flint, H. J. (2006). Whole-Genome Transcription Profiling Reveals Genes Up-Regulated by Growth on Fucose in the Human Gut Bacterium "Roseburia inulinivorans".. J. Bacteriol. 188: 4340-4349 [Abstract] [Full Text]  
  • Belenguer, A., Duncan, S. H., Calder, A. G., Holtrop, G., Louis, P., Lobley, G. E., Flint, H. J. (2006). Two Routes of Metabolic Cross-Feeding between Bifidobacterium adolescentis and Butyrate-Producing Anaerobes from the Human Gut.. Appl. Environ. Microbiol. 72: 3593-3599 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»