Supplementation of the Diet with High-Viscosity Beta-Glucan Results in Enrichment for Lactobacilli in the Rat Cecum

Abstract

BBn (BioBreeding) rats were fed casein-based diets supplemented with barley flour, oatmeal flour, cellulose, or barley ␤-glucans of high [HV] or low viscosity [LV] in order to measure the prebiotic effects of these different sources of dietary fiber. The dietary impact on the composition of the cecal microbiota was determined by the generation of denaturing gradient gel electrophoresis (DGGE) profiles of PCR-amplified 16S rRNA gene sequences. The DGGE profiles produced from the cecal microbiota of rats within each dietary group were similar, but consensus profiles generated from pooled bacterial DNAs showed differences between rat groups. Animals fed HV glucans (HV-fed rats) had DGGE consensus profiles that were 30% dissimilar from those of the other rat groups. A 16S rRNA gene fragment that was more conspicuous in the profiles of HV-fed animals than in those of cellulose-fed rats had sequence identity with Lactobacillus acidophilus. Measurements of L. acidophilus rRNA abundance (DNA-RNA hybridization), the preparation of cloned 16S rRNA gene libraries, and the enumeration of Lactobacillus cells (fluorescent in situ hybridization) showed that lactobacilli formed a greater proportion of the cecal microbiota in HV-fed rats. In vitro experiments confirmed that some lactobacilli utilize oligosaccharides (degree of polymerization, 3 or 4) present in ␤-glucan hydrolysates. The results of this study have relevance to the use of purified ␤-glucan products as dietary supplements for human consumption.

Assessment of technological characteristics of non-fat yoghurt manufactured with prebiotics and probiotic strains

“…The viable count was almost stable in C2 and T1 groups and a slight decrease was observed in the rest of the groups during the 21 days of storage. Several reports pointed out the ability of selected probiotic and yoghurt strains to utilize β-glucan (Snart et al 2006;Gee et al 2007). Our findings were also consistent with the results given by Jaskari et al (1998) regarding the promotion of growth by β-glucan and the viability of LAB.…”

Whole-Transcriptome Shotgun Sequencing (RNA-seq) Screen Reveals Upregulation of Cellobiose and Motility Operons of Lactobacillus ruminis L5 during Growth on Tetrasaccharides Derived from Barley β-Glucan

“…While apparently not essential for relative fitness in the human bowel, tetrasaccharide utilization can nevertheless be seen as an important trophic characteristic. It would allow an L. ruminis strain to share ecosystem resources with ␤-glucan degraders (9). The nutritional interaction demonstrated between Coprococcus sp.…”

“…ruminis has been cultured from bovine rumen contents and human feces, indicating that the species can inhabit environments rich in plant polymeric material. In a previously reported study (9), we observed that, while unable to grow in medium containing plant ␤-glucans (1:3,1:4-␤-D-glucans), L. ruminis cultures were able to utilize tetrasaccharide in ␤-glucan hydrolysate. ␤-Glucans are components of plant cells, especially of the endosperm of cereals such as barley, rye, sorghum, rice, and wheat.…”

Effect of Whole-Grain Barley on the Human Fecal Microbiota and Metabolome

“…Indeed, a prebiotic effect of ␤-glucans on the intestinal microbiota was also hypothesized (5). In particular, the positive effects of ␤-glucans on the growth of beneficial intestinal lactobacilli and bifidobacteria were shown in in vitro studies (20,21) and animal experiments (22,23). Nevertheless, other studies that also used animal models did not show significant effects of ␤-glucans on lactobacilli and/or bifidobacteria (24,25).…”