In vitro three-stage continuous fermentation of wheat arabinoxylan fractions and induction of hydrolase activity by the gut microflora.
In vitro fermentations were carried out by using a model of the human colon to stimulate microbial activities of gut bacteria. The model consisted of a three-stage culture system. Bacterial populations were evaluated under the effect of three types of arabinoxylan, a nonstarch polysaccharide derived from wheat, the water-unextractable arabinoxylan fraction (WU-AX), WU-AX pretreated with exogenous xylanase and the soluble water-extractable arabinoxylan fraction (WE-AX). The xylanase pretreated (WU-AX) had a stimulatory effect upon colonic bifidobacteria throughout all three vessels. Counts of Bacteroides spp. and Clostridium spp. were also both significantly reduced. Addition of the WU-AX substrates to the first vessel resulted in induction of bacterial synthesis of extracellular hydrolytic enzymes xylanase and ferulic acid esterase which are both required for bacterial metabolism of WU-AX; this induction was significantly greater with the xylanase treated WU-AX.
Vardakou
Maria
M
Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zografou Campus, 15780 Athens, Greece; Institute of Food Research, Norwich Research Park, Colney, NR4 7UA Norwich, UK.
Nueno Palop
Carmen
C
Gasson
Michael
M
Narbad
Arjan
A
Christakopoulos
Paul
P
D017931:DNA Primers; D004275:DNA, Ribosomal / Q000235:genetics; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism*; D005285:Fermentation; D005433:Flour; D006801:Humans; D006867:Hydrolases / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000201:enzymology*; D007420:Intestine, Large / Q000201:enzymology*; D007700:Kinetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014908:Triticum / Q000378:metabolism*; D014990:Xylans / Q000378:metabolism*
D017931:DNA Primers; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D014990:Xylans; C085118:arabinoxylan; D006867:Hydrolases; D043364:Endo-1,4-beta Xylanases