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United States Department of Agriculture

Agricultural Research Service


item Martin, S. A.
item Morrison Iii, Wiley
item Akin, Danny

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Because of the apparent added health benefits of dietary fiber in our diet, there has been continued interest in increasing the level of dietary fiber in humans. In this study, a bacterium found in low concentrations in the human colon which degrade dietary fiber was studied to evaluate how well it degraded grain brans and these brans after the more easily degraded sugars had been removed. An understanding of how mixed as well as pure cultures of bacteria degrade dietary fiber (thus providing energy) will help identify fiber-rich materials which can be used as dietary supplements in the human diet. Since most of the more easily degraded sugars are absorbed in the stomach and small intestines, this study showed that to study the action of fiber degrading bacteria in the colon, fiber with the more easily degraded sugars removed should be used.

Technical Abstract: Bacteroides ovatus is a Gram-negative obligate anaerobe that was isolated from the human colon and is capable of utilizing xylan. The objective of this study was to evaluate the ability of B. ovatus V975 to digest maize bran, oat bran, and wheat bran as well as the isolated cell walls from each bran source. Strain V975 was incubated in basal medium that contained either 0.1 or 0.3 g of each bran or each bran cell wall for 0, 24, 48, and 72 h. Acetate and succinate were the main products detected from each fermentation; however, less of each end product was produced from the isolated cell walls than from each bran. More of the oat bran was digested during the 72 h incubation than any other bran source. While each bran contained arabinose and xylose, more glucose, galactose, and mannose were utilized by strain V975 during the 72 h incubation than either pentose sugar. Compared to each bran, the bran cell walls had lower concentrations sof most sugars, and more glucose was utilized by strain V975 than any othe sugar. These results suggest that strain V975 preferentially utilizes glucose, galactose, and mannose in each bran, while glucose is the main sugar fermented in bran cell walls.

Last Modified: 06/22/2017
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