Time filter

Source Type

Wolverton Mill, United Kingdom

Osman A.,University of Reading | Tzortzis G.,Clasado Ltd | Rastall R.A.,University of Reading | Charalampopoulos D.,University of Reading
Journal of Agricultural and Food Chemistry | Year: 2013

The bifidobacterial β-galactosidase (BbgIV) was produced in E. coli DH5α at 37 and 30 °C in a 5 L bioreactor under varied conditions of dissolved oxygen (dO2) and pH. The yield of soluble BbgIV was significantly (P < 0.05) increased once the dO2 dropped to 0-2% and remained at such low values during the exponential phase. Limited dO2 significantly (P < 0.05) increased the plasmid copy number and decreased the cells growth rate. Consequently, the BbgIV yield increased to its maximum (71-75 mg per g dry cell weight), which represented 20-25% of the total soluble proteins in the cells. In addition, the specific activity and catalytic efficiency of BbgIV were significantly (P < 0.05) enhanced under limited dO2 conditions. This was concomitant with a change in the enzyme secondary structure, suggesting a link between the enzyme structure and function. The knowledge generated from this work is very important for producing BbgIV as a biocatalyst for the development of a cost-effective process for the synthesis of prebiotic galactooligosaccharides from lactose. © 2013 American Chemical Society.

Drakoularakou A.,University of Reading | Tzortzis G.,Clasado Ltd | Rastall R.A.,University of Reading | Gibson G.R.,University of Reading
European Journal of Clinical Nutrition | Year: 2010

Background/Objectives: Prebiotics have attracted interest for their ability to positively affect the colonic microbiota composition, thus increasing resistance to infection and diarrhoeal disease. This study assessed the effectiveness of a prebiotic galacto-oligosaccharide mixture (B-GOS) on the severity and/or incidence of travellers' diarrhoea (TD) in healthy subjects.Subjects/Methods: The study was a placebo-controlled, randomized, double blind of parallel design in 159 healthy volunteers, who travelled for minimum of 2 weeks to a country of low or high risk for TD. The investigational product was the B-GOS and the placebo was maltodextrin. Volunteers were randomized into groups with an equal probability of receiving either the prebiotic or placebo. The protocol comprised of a 1 week pre-holiday period recording bowel habit, while receiving intervention and the holiday period. Bowel habit included the number of bowel movements and average consistency of the stools as well as occurrence of abdominal discomfort, flatulence, bloating or vomiting. A clinical report was completed in the case of diarrhoeal incidence. A post-study questionnaire was also completed by all subjects on their return. Results: Results showed significant differences between the B-GOS and the placebo group in the incidence (P<0.05) and duration (P<0.05) of TD. Similar findings occurred on abdominal pain (P<0.05) and the overall quality of life assessment (P<0.05). Conclusions: Consumption of the tested galacto-oligosaccharide mixture showed significant potential in preventing the incidence and symptoms of TD. © 2010 Macmillan Publishers Limited All rights reserved.

Osman A.,University of Reading | Symeou S.,University of Reading | Trisse V.,Montpellier University | Watson K.A.,University of Reading | And 2 more authors.
Biochemical Engineering Journal | Year: 2014

The bifidobacterial β-galactosidase BbgIV was immobilised on DEAE-Cellulose and Q-Sepharose via ionic binding and on amino-ethyl- and glyoxal-agarose via covalent attachment, and was then used to catalyse the synthesis of galactooligosaccharides (GOS). The immobilisation yield exceeded 90% using ionic binding, while it was low using amino-ethyl agarose (25-28%) and very low using glyoxal agarose (<3%). This was due to the mild conditions and absence of chemical reagents in ionic binding, compared to covalent attachment. The maximum GOS yield obtained using DEAE-Cellulose and Q-Sepharose was similar to that obtained using free BbgIV (49-53%), indicating the absence of diffusion limitation and mass transfer issues. For amino-ethyl agarose, however, the GOS yield obtained was lower (42-44%) compared to that obtained using free BbgIV. All the supports tried significantly (P<. 0.05) increased the BbgIV operational stability and the GOS synthesis productivity up to 55. °C. Besides, six successive GOS synthesis batches were performed using BbgIV immobilised on Q-Sepharose; all resulted in similar GOS yields, indicating the possibility of developing a robust synthesis process. Overall, the GOS synthesis operation performance using BbgIV was improved by immobilising the enzyme onto solid supports, in particular on Q-Sepharose. © 2013 Elsevier B.V.

Osman A.,University of Reading | Tzortzis G.,Clasado Ltd | Rastall R.A.,University of Reading | Charalampopoulos D.,University of Reading
Journal of Agricultural and Food Chemistry | Year: 2012

The individual contributions of four β-galactosidases present in Bifidobacterium bifidum NCIMB 41171 toward galactooligosaccharide (GOS) synthesis were investigated. Although the β-galactosidase activity of the whole cells significantly decreased as a function of temperature (40-75 °C), GOS yield was at its maximum at 65 °C. Native-PAGE of the whole cells showed that the contributions of BbgIII and BbgIV to GOS synthesis increased as the temperature increased. Moreover, BbgIII and BbgIV were found to be more temperature stable and to produce a higher GOS yield than BbgI and BbgII, when used in their free form. The GOS yield using BbgIV was 54.8% (percent of total carbohydrates) and 63.9% (percent lactose converted to GOS) at 65 °C from 43% w/w lactose. It was shown that BbgIV is the most important β-galactosidase in B. bifidum NCIMB 41171 and can be used for GOS synthesis at elevated temperatures. © 2011 American Chemical Society.

Searle L.E.J.,Animal Health and Veterinary Laboratories Agency AHVLA | Jones G.,Animal Health and Veterinary Laboratories Agency AHVLA | Tzortzis G.,Clasado Ltd | Woodward M.J.,Animal Health and Veterinary Laboratories Agency AHVLA | And 5 more authors.
Journal of Functional Foods | Year: 2012

Previous in vivo murine oral challenge studies have shown that the galactooligosaccharide containing product, BiMuno®, reduced colonisation of S. Typhimurium. To gain further insights into the mechanism of reduced colonisation, we wished to test the hypothesis that the low molecular weight fractions of BiMuno® or a specific low molecular weight fraction may have direct immuno-modulatory effects on murine macrophages. Cytokine responses of murine macrophages in response to the commercially available product, BiMuno®, a basal solution BiMuno® without GOS, purified low molecular weight fractions (referred to as GOS), and the individual fractions of GOS (DP2, 3 and ≥4, with each fraction representing the increasing degree of complex polymerisation) were determined in vitro and ex vivo. These studies demonstrated that BiMuno®, significantly stimulated both pro- and anti-inflammatory cytokines in vitro (P≤ 0.0394). Furthermore, the data indicate that the low molecular weight fractions may be the primary stimulant of BiMuno® and specifically its tri (DP3) and ≥tetra-saccharide (DP ≥ 4) fractions (P≤ 0.0394). © 2012.

Discover hidden collaborations