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Study on the Utilization of Xylo-Oligosaccharides by Lactobacillus Sp. with an Emphasis on the Biochemical Characterization of a Xylanolytic Enzyme.

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Title Study on the Utilization of
Xylo-Oligosaccharides by Lactobacillus Sp. with an
Emphasis on the Biochemical Characterization of a
Xylanolytic Enzyme.
 
Creator Lyned, D. Lasrado
 
Subject 05 Enzymes
04 Wheat
 
Description Xylo-oligosaccharides (XOS) are non-digestible oligosaccharides which
are classified under emerging prebiotics. The ability to utilize XOS varies
considerably among lactobacilli and is dependent on the efficiency of their
xylanolytic enzymes and sugar transporters. The present study is envisaged
to understand the utilization of XOS by Lactobacillus sp. by characterizing
the major xylanolytic enzyme and identifying sugar transporters involved in
the uptake of XOS. It also touches upon the health benefits of the synbiotic
combination of XOS and lactobacilli in terms of antioxidant potential as well
as cholesterol lowering property. XOS used in this study was isolated from
wheat bran water unextractable portion. The major oligosaccharides in the
XOS mixture were identified as, xylobiose (Xyl-(1→4) β-Xyl) and arabinoxylotriose
(β-Xyl-(3→1-α-Ara)-1→4-β-Xyl). Among the seven strains of
lactobacilli studied, Lactobacillus brevis NCDC 01 showed the highest
efficiency to utilize XOS. Intracellular β-D-xylosidase was the major
xylanolytic enzyme involved in the metabolism of XOS. Three sequential
steps i.e. ultrafiltration, ion exchange chromatography and gel permeation
chromatography were employed to purify the enzyme. The estimated
molecular mass of the purified enzyme was found to be ~58 kDa. The
temperature and pH optima of the enzyme were found to be 40°C and 6.0,
respectively. The enzyme does not require any metal ion for stability or
activity and under optimum conditions exhibited a Km and Vmax of 0.87 mM
and 0.14 μmoles/min respectively. Presence of an intracellular β-Dxylosidase
indicated that XOS may first be transported into the bacterial cell
by sugar transporters and subsequently digested to xylose. Gene expression
analysis by real-time quantitative PCR (qPCR) showed a significant upregulation
of genes putatively coding for the components of the ATP-Binding
Cassette (ABC transporter system).
Synbiotic combination of XOS and Lactobacillus brevis NCDC 01
showed higher ability to reduce the cholesterol content in media and
deconjugate bile salts compared to the combination of XOS and other tested
strains. XOS was used in combination with selected Lactobacillus sp. in
preparation of synbiotic fermented milk and their antioxidant potential was
evaluated. Ferric reducing power as well as DPPH radical scavenging activity
were significantly (p
 
Contributor Muralikrishna, G.
 
Date 2015
 
Type Thesis
NonPeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://ir.cftri.com/11932/1/Lyned%20Dafny%20Lasrado%2C%20Ph.D%20Thesis%2C%20March%202015.pdf
Lyned, D. Lasrado (2015) Study on the Utilization of Xylo-Oligosaccharides by Lactobacillus Sp. with an Emphasis on the Biochemical Characterization of a Xylanolytic Enzyme. PhD thesis, University of Mysore.