Prebiotic effects of diet supplemented with the cultivated red seaweed Chondrus crispus or with fructo-oligo-saccharide on host immunity, colonic microbiota and gut microbial metabolites.

Jinghua Liu,Alan T Critchley,Balakrishnan Prithiviraj,Christopher W Kirby,Franklin Evans,Saveetha Kandasamy,Jeff Hafting,Tobias Karakach,Junzeng Zhang

doi:10.1186/s12906-015-0802-5

Abstract

BackgroundGastrointestinal microbial communities are diverse and are composed of both beneficial and pathogenic groups. Prebiotics, such as digestion-resistant fibers, influence the composition of gut microbiota, and can contribute to the improvement of host health. The red seaweed Chondrus crispus is rich in dietary fiber and oligosaccharides, however its prebiotic potential has not been studied to date.MethodsPrebiotic effects were investigated with weaning rats fed a cultivated C. crispus-supplemented diet. Comparison standards included a fructo-oligo-saccharide (FOS) diet and a basal diet. The colonic microbiome was profiled with a 16S rRNA sequencing-based Phylochip array. Concentrations of short chain fatty acids (SCFAs) in the feacal samples were determined by gas chromatography with a flame ionization detector (GC-FID) analysis. Immunoglobulin levels in the blood plasma were analyzed with an enzyme-linked immunosorbent assay (ELISA). Histo-morphological parameters of the proximal colon tissue were characterized by hematoxylin and eosin (H&E) staining.ResultsPhylochip array analysis indicated differing microbiome composition among the diet-supplemented and the control groups, with the C. crispus group (2.5 % supplementation) showing larger separation from the control than other treatment groups. In the 2.5 % C. crispus group, the population of beneficial bacteria such as Bifidobacterium breve increased (4.9-fold, p = 0.001), and the abundance of pathogenic species such as Clostridium septicum and Streptococcus pneumonia decreased. Higher concentrations of short chain fatty acids (i.e., gut microbial metabolites), including acetic, propionic and butyric acids, were found in faecal samples of the C. crispus-fed rats. Furthermore, both C. crispus and FOS supplemented rats showed significant improvements in proximal colon histo-morphology . Higher faecal moisture was noted in the 2.5 % C. crispus group, and elevated plasma immunoglobulin (IgA and IgG) levels were observed in the 0.5 % C. crispus group, as compared to the basal feed group.ConclusionsThe results suggest multiple prebiotic effects, such as influencing the composition of gut microbial communities, improvement of gut health and immune modulation in rats supplemented with cultivated C. crispus.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-015-0802-5) contains supplementary material, which is available to authorized users.

Highlights

Gastrointestinal microbial communities are diverse and are composed of both beneficial and pathogenic groups
There was a minor increase in the weight of liver in all fiber-supplemented groups, the change was not statistically significant (Fig. 1b) as compared to the control rats.The C. crispus supplemented diet C2.5 increased faecal moisture after 21 days of feeding (increased by 17 % (p = 0.04)), as compared to the control group (Fig. 1c)
Based on our previous observations on the immunemodulation effect of C. crispus [29], immunoglobulin levels in rats were expected to be influenced by dietary C. crispus

Summary

Introduction

Gastrointestinal microbial communities are diverse and are composed of both beneficial and pathogenic groups. Prebiotics, such as digestion-resistant fibers, influence the composition of gut microbiota, and can contribute to the improvement of host health. Beneficial gut bacteria (i.e., probiotics), such as Bifidobacterium spp. and Lactobacillus spp. promote animal and human health by providing nutritional metabolites, such as short chain fatty acids, through selective fermentation of digestion-resistant carbohydrates [2]. When children with food allergy-related severe atopic eczema were fed Lactobacillus rhamnosus and Bifidobacterium lactis, they showed significant improvement in clinical symptoms, as compared to the placebo group [14, 15]. Consumption of milk fortified with prebiotic oligosaccharide and the probiotic bacterium B. lactis was reported to reduce episodes of dysentery, pneumonia, and severe acute lower respiratory infection (as compared to the placebo group), in 1–4 year old children, who had limited access to hygienic conditions [17]

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