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.
BACKGROUND
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. The red seaweed Chondrus crispus is rich in dietary fiber and oligosaccharides, however its prebiotic potential has not been studied to date.


METHODS
Prebiotic 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.


RESULTS
Phylochip 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.


CONCLUSIONS
The 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.
Department of Environmental Sciences, Dalhousie University, Truro, NS, B2N 2R8, Canada. julialiu329@gmail.com.
Jinghua
J
Liu
Department of Environmental Sciences, Dalhousie University, Truro, NS, B2N 2R8, Canada. Saveetha.Kandasamy@AGR.GC.CA.
Saveetha
S
Kandasamy
Natural Products Chemistry, National Research Council of Canada, Halifax, B3H 3Z1, Canada. Junzeng.Zhang@nrc-cnrc.gc.ca.
Junzeng
J
Zhang
Crops and Livestock Research Centre, Agriculture and Agri-Food Canada, Charlottetown, PE, C1A 4N6, Canada. chris.kirby@agr.gc.ca.
Christopher W
CW
Kirby
Natural Products Chemistry, National Research Council of Canada, Halifax, B3H 3Z1, Canada. Tobias.Karakach@nrc-cnrc.gc.ca.
Tobias
T
Karakach
Acadian Seaplants Limited, 30 Brown Ave., Dartmouth, NS, B3B 1X8, Canada. jth@acadian.ca.
Jeff
J
Hafting
Acadian Seaplants Limited, 30 Brown Ave., Dartmouth, NS, B3B 1X8, Canada. atc@acadian.ca.
Alan T
AT
Critchley
Acadian Seaplants Limited, 30 Brown Ave., Dartmouth, NS, B3B 1X8, Canada. fde@acadian.ca.
Franklin
F
Evans
Department of Environmental Sciences, Dalhousie University, Truro, NS, B2N 2R8, Canada. BPrithiviraj@dal.ca.
Balakrishnan
B
Prithiviraj
D000818:Animals; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D044723:Chondrus / Q000737:chemistry*; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D004043:Dietary Fiber / Q000494:pharmacology; D019587:Dietary Supplements; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D000069196:Gastrointestinal Microbiome / Q000187:drug effects; D007109:Immunity / Q000187:drug effects; D007136:Immunoglobulins / Q000097:blood*; D008297:Male; D009844:Oligosaccharides / Q000494:pharmacology*; D056692:Prebiotics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017207:Rats, Sprague-Dawley; D012624:Seaweed
D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; D007136:Immunoglobulins; D009844:Oligosaccharides; D056692:Prebiotics; D012336:RNA, Ribosomal, 16S