Fermentation properties and potential prebiotic activity of Bimuno® galacto-oligosaccharide (65 % galacto-oligosaccharide content) on in vitro gut microbiota parameters

Abstract

Prebiotic oligosaccharides have the ability to generate important changes in the gut microbiota composition that may confer health benefits to the host. Reducing the impurities in prebiotic mixtures could expand their applications in food industries and improve their selectivity and prebiotic effect on the potential beneficial bacteria such as bifidobacteria and lactobacilli. This study aimed to determine the in vitro potential fermentation properties of a 65 % galacto-oligosaccharide (GOS) content Bimuno® GOS (B-GOS) on gut microbiota composition and their metabolites. Fermentation of 65 % B-GOS was compared with 52 % B-GOS in pH- and volume-controlled dose-response anaerobic batch culture experiments. In total, three different doses (1, 0·5 and 0·33 g equivalent to 0·1, 0·05 and 0·033 g/l) were tested. Changes in the gut microbiota during a time course were identified by fluorescence in situ hybridisation, whereas small molecular weight metabolomics profiles and SCFA were determined by 1H-NMR analysis and GC, respectively. The 65 % B-GOS showed positive modulation of the microbiota composition during the first 8 h of fermentation with all doses. Administration of the specific doses of B-GOS induced a significant increase in acetate as the major SCFA synthesised compared with propionate and butyrate concentrations, but there were no significant differences between substrates. The 65 % B-GOS in syrup format seems to have, in all the analysis, an efficient prebiotic effect. However, the applicability of such changes remains to be shown in an in vivo trial.

Keywords: B-GOS Bimuno galacto-oligosaccharide; Bimuno® galacto-oligosaccharides; Fluorescence in situ hybridisation; GOS galacto-oligosaccharide; Microbiota composition; Prebiotic activity; SCFA.

Fig. 1

¹H-NMR data analysis. (a–c) Principal component (PC) analysis (PCA) score plot B-GOS 65 % – T4 and PCA score plot B-GOS 52 % – T4, respectively, show a clear separation during the first 4 h of fermentation due to dose–response effect. (b–d) PCA score plot B-GOS 65 % – T8 and PCA score plot B-GOS 52 % – T8, respectively, show how the dose effect is lost after 4 h of fermentation. (e) The colour plot illustrates the main compound, acetate, influencing the separation. The 65 % B-GOS and 52 % B-GOS were tested at 1, 0·5 and 0·33 g equivalent to 0·1, 0·05 and 0·033 g/l. a, b: , 65 % B-GOS 0·33 g; , 65 % B-GOS 0·5 g; , 65 % B-GOS 1 g; c, d: , 52 % B-GOS 0·33 g; , 52 % B-GOS 0·5 g; , 52 % B-GOS 1 g.