Role of Intestinal Microbiota in Ulcerative Colitis

Process Biochemistry 46 (2011) 1039–1049
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Process Biochemistry
journal homepage: www.elsevier.com/locate/procbio
Tailored enzymatic production of oligosaccharides from sugar beet pectin and
evidence of differential effects of a single DP chain length difference on human
faecal microbiota composition after in vitro fermentation
Jesper Holck a , Karin Hjernø b , Andrea Lorentzen b , Louise K. Vigsnæs c , Lene Hemmingsen c ,
Tine R. Licht c , Jørn D. Mikkelsen a , Anne S. Meyer a,∗
a Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
b Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
c National Food Institute, Division of Microbiology and Risk Assessment, Technical University of Denmark, 2860 Søborg, Denmark
article info
Article history:
Received 27 September 2010
Received in revised form 9 January 2011
Accepted 11 January 2011
Keywords:
Sugar beet pectin
Homogalacturonan oligomers
Rhamnogalacturonan oligomers
Ion exchange chromatography
In vitro fermentation
Human faeces
1. Introduction
abstract
Side-streams from agricultural industries are the subject of a
number of studies to generate added-value products. From the
sugar industry, sugar beet pulp comprises more than 4 million
tons/year in the European Community. Sugar beet pectin is a major
fraction of this renewable resource, but has so far only been utilized
commercially for a limited number of applications [1]. Pectin,
including sugar beet pectin, is one of the most structurally complex
types of polysaccharides in nature. Pectin is generally defined
as a heteropolysaccharide predominantly containing galacturonic
acid (GalA) residues that are organized in a pattern of “smooth”
Abbreviations: HG, homogalacturonan; RGI, rhamnogalacturonan I; SB, sugar
beet.
∗ Corresponding author at: Center for Bioprocess Engineering, Department of
Chemical and Biochemical Engineering, Technical University of Denmark, Building
229, DTU, 2800 Kgs. Lyngby, Denmark. Tel.: +45 45 25 28 00; fax: +45 45 88 22 58.
E-mail address: am@kt.dtu.dk (A.S. Meyer).
1359-5113/$ – see front matter © 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.procbio.2011.01.013
Sugar beet pectin was degraded enzymatically and separated by ion exchange chromatography into series
of highly purified homogalacturonides and rhamnogalacturonides. MALDI-TOF/TOF mass-spectrometry
was used to determine sizes and structural features. The methodology was based on the sequential use
of monocomponent enzymes that were selected to target specific substructures in the sugar beet pectin.
Notably pectin lyase and rhamnogalacturonan I lyase were used, which allowed detection of the resulting
cleavage products by UV spectroscopy. Seven different homogalacturonides (HG) with degrees of polymerization
(DP) from 2 to 8 and six different rhamnogalacturonide (RGI) structures, ranging from DP4
to 6 with defined galactose substitutions were purified. Total recoveries of 200 mg homogalacturonides
and 67 mg rhamnogalacturonides per gram sugar beet pectin were obtained. This integrated biorefining
method provides an option for advanced upgrading of sugar beet pectin into HG and RGI oligosaccharides
of defined size and structure. In vitro microbial fermentation by human faecal samples (n = 9) showed a
different response to the DP4 and DP5 HG structures on the ratio between Bacteroidetes and Firmicutes.
This indicates that pectic oligosaccharides with only slightly different structures have significantly different
biological effects. This is the first report of pectic oligosaccharide activity on gut bacterial populations
related to the metabolic syndrome associated with obesity.
© 2011 Elsevier Ltd. All rights reserved.
homogalacturonan (HG) regions and ramified “hairy” rhamnogalacturonan
I (RGI) regions in which neutral sugars are present as
side chains. HG consists of linear stretches of �-1,4-linked galacturonic
acid residues, which are partially methoxylated at the carboxyl
group and O-acetylated on O-2 and/or O-3. The length of HG in
sugar beet pectin is relatively shorter than the HG from citrus and
apple [1]. The acetylation in sugar beet pectin can be as high 50%
as reported by Levigne et al. [2]. The backbone of RGI is composed
of the repeating disaccharide [→2)-�-l-Rhap–(1→4)-�-d-GalpA-
(1→], and, depending on the source [3], 20–80% of the rhamnose
moieties may be substituted at the O-4 position with arabinan
(�-1,5-linked arabinose with some �-l-araf substitutions at C-2
or C-3), galactan (�-1,4-linked galactose) and/or arabinogalactan
(Fig. 1A). RGI can also be O-acetylated at the O-3 position of galacturonic
acid. The amount of RGI in sugar beet pectin is relatively
higher compared to apple and citrus pectin, comprising up to 25% of
the dry weight [4]. Furthermore RGI side chains in sugar beet pectin
are particularly rich in arabinose moieties [5] which are substituted
with ferulic acid (approximately 1% (w/w). Most of the ferulic acids
are bound as monomers, but some as various types of dimers [6].