The bacterial metabolism of carbohydrates used in tests of intestinal permeability

Qureishy, Gulzar A.

(1984)

Qureishy, Gulzar A. (1984) The bacterial metabolism of carbohydrates used in tests of intestinal permeability.

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Abstract

Carbohydrates have been used for tests of intestinal function for many years and the impaired absorption of carbohydrates in the intestinal lumen is either due to the damaged intestinal absorptive surface, as in coeliac disease etc., in some types of acute gastroenteritis , when the absorptive area is reduced by villous atrophy , or due to the bacterial overgrowth in the small intestinal lumen as in blind loop syndrome , some types of malabsorption , which possibly produce alteration in the morphology of the intestinal mucosa. Defective transport of sugars from the intestinal lumen coupled with the impaired absorption of different nutrients produce a typical gastrointestinal disease in tropical areas , 'Tropical Sprue'. D-Xylose , L-rhamnose and 3-0-methyl-a-D-glucose are used as markers for the permeability of the small intestine etc. The D-xylose absorption test has found increasing acceptance as an index of carbohydrate absorption and most sharply and consistently reduced values of absorption are usually found in patients with coeliac disease and tropical sprue . Despite their widespread clinical use , little is known about the biochemical nature of microbial uptake and degradation of these sugars by the human flora .Therefore the principle aim of the present study was to establish the utilization of these sugars by human intestinal organisms , and other subsequent metabolism and quantification of fermentation products . Fifty-six strains of intestinal bacteria were in vitro incubated under both aerobic and anaerobic conditions seperately with the threeindividual sugar-containing media . None of these organisms was ableto metabolise 3-0-methyl- [alpha]-D-glucose . Some organisms were alsounable to metabolise D-xylose and L-rhamnose; however others , e.g.Bacteroides and Enterobacteria , metabolised them extensively rangingfrom 30-100% rhamnose ; 25-68% xylose , and 40-70% rhamnose ; 30-35% xylose of the total carbohydrate supplied to Enterobacteria and Bacteroides respectively . With Enterobacteria , the extent of aerobic utilizations were 3-5 fold higher than anaerobic ones. The D-xylose and L-rhamnose were foundto be utilized simultaneously by Enterobacteria and Bacteroides.D-Glucose caused a marked inhibition of D-xylose in Escherichia coliand Enterobactor aerogenes , but L-rhamnose is utilized simultaneouslywith glucose in Enterobacter aerogenes .Quantitative analysis of the fermentation products of both D-xylose and L-rhamnose indicated that a variety of non-gaseous metabolites were produced and among them acetic , propionic , lactic and succinic acid were more prominent .In addition , the bacterial transport system of these carbohydrates were studied by an optical method (Plasmolysis) , and also by the use of radioactive sugars , D [U-14C] xylose and 3-0-methyl-D[U-14C] glucose .

Information about this Version

This is a Accepted version
This version's date is: 1984
This item is not peer reviewed

Link to this Version

https://repository.royalholloway.ac.uk/items/88213fdf-5e22-4e07-8769-499b75429a63/1/

Item TypeThesis (Masters)
TitleThe bacterial metabolism of carbohydrates used in tests of intestinal permeability
AuthorsQureishy, Gulzar A.
Uncontrolled KeywordsMicrobiology; Biological Sciences; Bacterial; Carbohydrates; Carbohydrates; Intestinal; Metabolism; Permeability; Tests; Used
DepartmentsDepartment of Biochemistry

Identifiers

ISBN978-1-339-60632-3

Deposited by () on 01-Feb-2017 in Royal Holloway Research Online.Last modified on 01-Feb-2017

Notes

Digitised in partnership with ProQuest, 2015-2016. Institution: University of London, Royal Holloway College (United Kingdom).


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