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Journal of Nutrition and Metabolism
Volume 2013 (2013), Article ID 540967, 5 pages
http://dx.doi.org/10.1155/2013/540967
Research Article

Preliminary Studies Demonstrating Acetoclastic Methanogenesis in a Rat Colonic Ring Model

1Departments of Pediatrics, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
2Montreal Children’s Hospital Research Institute, McGill University, Montreal, QC, Canada
3Pediatric Gastrointestinal Unit, Massachusetts General Hospital, 114 16th Street (114-3503), Charlestown, MA 02129-4004, USA

Received 31 March 2013; Accepted 18 June 2013

Academic Editor: T. R. Ziegler

Copyright © 2013 Edward A. Carter and Ronald G. Barr. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Washed rat colonic rings were incubated in closed flasks under N2 at physiologic pH and temperature levels. In the absence of an exogenous substrate, negligible H2 but some CH4 concentrations were detected in vitro after one hour of incubation, but high concentrations (H2 > 100 ppm, CH4 > 10 ppm) of both gases were found after 24 hours of culture. Production of H2 and CH4 by the washed colonic rings was stimulated by lactose addition. Maximum H2 production occurred at about pH 7.0, while maximum CH4 production occurred between pH 4.0 and 6.0. The increased production of both gases at 24 hours was associated with dramatic increases (104-fold) in anaerobic bacteria colony counts on the colonic rings and in the incubation media, as well as dramatic increases (100-fold) in acetate concentrations in the media, while lactate concentrations first rose and then fell significantly. These results suggest that gas production in colonic ring preparations is subject to quantitative changes in microbiota, pH, and metabolite formation analogous to in vivo conditions. In addition, microbiota firmly attached to colonic tissue appears to utilize colonic tissue to support its growth in the absence of an exogenous substrate.