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Applied and Environmental Microbiology, April 2000, p. 1321-1327, Vol. 66, No. 4
German Institute of Human Nutrition
Potsdam-Rehbrücke, D-14558 Bergholz-Rehbrücke, Germany
Received 5 October 1999/Accepted 8 January 2000
A complete human fecal flora and cultures of defined species
obtained from fecal flora were investigated in vitro to determine their
ability to ferment the dietary fiber pectin. Bacteroides thetaiotaomicron was tested as a pectin-degrading microorganism alone and in coculture with Escherichia coli.
Macromolecular pectins with different degrees of esterification
were used as substrates in microbial degradation studies. The levels
of oligogalacturonic acids formed in batch cultures were estimated
during a 24- or 48-h incubation period by using
high-performance thin-layer chromatography and
high-performance anion-exchange chromatography. The spectrum and
the amount of unsaturated oligogalacturonic acids formed as intermediate products of pectin fermentation changed permanently in the
culture media during incubation with the complete fecal flora. After
24 h, no oligogalacturonic acids were detected. The pectin-degrading activities of pure cultures of B. thetaiotaomicron were lower than the pectin-degrading activity of
a complete fecal flora. Cocultures of B. thetaiotaomicron
and E. coli exhibited intermediate levels of degradation
activity. In pure cultures of E. coli no pectin-degrading
activity was found. Additionally, the rate of pectin degradation was
affected by the degree of esterification of the substrate. Saturated
oligogalacturonic acids were not found during pectin fermentation. The
disappearance of oligogalacturonic acids in the later stages of
fermentation with both the complete fecal flora and B. thetaiotaomicron was accompanied by increased formation of
short-chain fatty acids.
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Degradation of Pectins with Different Degrees of Esterification
by Bacteroides thetaiotaomicron Isolated from Human
Gut Flora
*
Corresponding author. Mailing address: German Institute
of Human Nutrition Potsdam-Rehbrücke, Department of Food Science and Preventive Nutrition, D-14558 Bergholz-Rehbrücke, Germany. Phone: 49 33200 88268. Fax: 49 33200 88444. E-mail:
dongo{at}www.dife.de.
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