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It is well known that dietary fibre affects bacterial growth and metabolic activity in the gastrointestinal tract of mammals. Kiwifruit is characterized for having high levels of dietary fibre, of which the majority belong from soluble fraction. Therefore, a huge variety of beneficial effects are proposed; however, the effects of kiwifruit on the intestinal microbiota have not been specifically demonstrated, but anecdotal evidence suggests that their positive effects may in part be elicited via improved composition of the microbiota, working as a good prebiotic source. The aim of this study was to investigate whether green kiwifruit modulates the composition of colonic microbiota in growing pigs.
Thirty-two pigs were fed the control diet or one of the three diets containing cellulose, freeze-dried kiwifruit or kiwifruit fibre as the sole fibre source for 14-day study. After euthanasia, the abdomen was opened and the colon was dissected out. The digesta was carefully collected to plastic bags and frozen at -80ºC until DNA extraction for molecular biology analysis.
A Ward’s dendrogram of similarity cluster analysis on PCR-DGGE gels revealed that inclusion of freeze-dried kiwifruit and kiwifruit fibre into diets altered the bacterial community, indicating the presence of two distinct clusters. Quantification of different bacterial groups by qPCR demonstrated that pigs fed the freeze-dried kiwifruit or kiwifruit fibre diets had a significantly higher number (P<0.05) of total bacteria and Bacteroides group and a lower number of Enterobacteria and Escherichia coli group, as well as a greater ratio of Lactobacillus to Enterobacteria when compared to pigs fed the control or cellulose diets.
As a conclusion, green kiwifruit, mainly because of fibre, modulated the colonic microbiota, leading to an improved intestinal environment in growing pigs. On the other hand, the study provides a significance importance as is the first report regarding the effect of green kiwifruit on gut microbiota.
KS Han, P Balan, F Molist-Gasa and M Boland. Green kiwifruit modulates the colonic microbiota in growing pigs. 2011. Letters in Applied Microbiology, 52:379-385.