Research On The Prebiotic Effectiveness Of Cereal β-glucan Both In Vivo And In Vitro

In this paper, we compared the effects of oat β-glucan and barley β-glucan on thegut health in an in vivo experiment; meanwhile, studied the influence of cerealβ-glucan and the acidolysis products of cereal β-glucan on the growth of the probioticcultures Lactobacillus helveticus, Lactobacillus acidophilus, Lactobacillus rhamnosusand Bifidobacterium longum in an in vitro experiment.120male Sprague-Dawley rats were divided into five groups (CON, OGL, OGH,BGL and BGH). There were24rats in each group. The OGL and OGH wereadministered oat β-glucan by intragastric gavage at dose of0.35g/(kg BW) and0.70g/(kg BW) daily for6weeks as well as BGL and BGH were administered barleyβ-glucan. The CON was received normal saline. Intestinal health related indexes wereanalyzed at baseline, week3, week6and week7(after terminating cereal β-glucanadministration for1week). The results showed that cereal β-glucan reduced the foodintake, rate of weight gain, fecal pH, fecal ammonia levels and fecal β-glucuronidaseactivity (p<0.05), improved the fresh feces weight, dry feces weight and faecal watercontent (p<0.05). The azoreductase activity in rats administrated oat β-glucan at highdose significantly decreased at week6, compared to the control group (P＜0.05).Moreover, the population of Lactobacillus and Bifidobacterium increased (p<0.05),whereas the number of Enterobacteriaceae decreased (p<0.05) during the period ofcereal β-glucan administration. These results suggested that cereal β-glucan mightexert favorable effects on improving intestinal health in a dose-dependent manner. Buton the whole, oat β-glucan would have better effects on gut health than barleyβ-glucan at the same dosage. In addition, both oat β-glucan and barley β-glucan couldincrease the number of goblet cell and gland, shorten the villus of rats in adose-dependent manner.Cereal β-glucan and the acidolysis products of cereal β-glucan were added inbasal media for their effects on the growth of the probiotic cultures Lactobacillushelveticus, Lactobacillus acidophilus, Lactobacillus rhamnosus and Bifidobacteriumlongum. The results of this study showed that all four probiotic strains were not able to utilize cereal β-glucan. However, the probiotic cultures Lactobacillus helveticus,Lactobacillus rhamnosus and Bifidobacterium longum were able to grow to highyields using acidolysis products of cereal β-glucan in a dose-dependent manner whenthe added concentration of acidolysis products of cereal β-glucan was between0.5~2.0g/L. At the same level, acidolysis products of barley β-glucan had a bettereffect on the growth of the probiotic cultures than that of oat β-glucan. Whereafter,growth of the three strains was monitored in a basal medium supplemented withacidolysis products of cereal β-glucan, as the sole carbon source. The results revealedthat growth of the three probiotic cultures in basal medium containing acidolysisproducts of cereal β-glucan although increased as compared with the reference basalmedia, were significantly less than that in the glucose media, and acidolysis productsof barley β-glucan tended to be utilized better than that of oat β-glucan.All of the above data, obtained from both in vivo and in vitro experiments, insuggest that cereal β-glucan are unlikely to directly provide a carbon source topromote the proliferation of probiotic bacteria in the intestinal tract. However, thebeneficial bacteria tend to be able to cross-feed on oligomers resulting from thehydrolysis of β-glucan. In terms of improving the environment and promoting thebeneficial microorganism in bowel, water-insoluble β-glucan may provide anadvantage over the water-soluble β-glucan, because water-insoluble β-glucans aremore slowly fermentable.