Isolated White Lupin Proteins Beneficially Modulate the Intestinal Microbiota Composition in Rats

Background: Previous work has shown that the mostly beneficial modulation of intestinal microbiota generally found with legume-based diets is likely to be due, at least in part, to their constituent protein components. Objectives: The faecal microbiota composition was studied in rats fed diets differing only in their constituent proteins. Methods: Rats (n = 10/group) were fed for 28 days diets based in milk [(lactalbumin (LA), casein (CAS)], or white lupin (Lupinus albus) protein isolate (LPI). Results: Significant differences among the three groups in bacteria composition and functionality were found by both qPCR and Illumina sequencing analysis. Significant (p < 0.01) differences were found by ANOSIM and Discriminant Analysis among groups at the family, genus and species levels in both microbiota composition and functionality. A number of groups able to explain the differences between animal (casein, lactalbumin) and lupin proteins were revealed by LEfSe and PCA analysis. Specifically, feeding the CAS diet resulted in lower Bifidobacteria and Lactobacilli compared to the other diets, and the LPI diet gave place to lower Enterobacteria than CAS, and lower Escherichia/Shigella than LA and CAS. Differences in the LA group were attributable to Bifidobacterium spp., Collinsella spp. (in particular C. stercoris), Bacteroides spp., Eubacterium spp. (in particular E. dolichum), Roseburia spp. (in particular R. faecis), and Oscillospira spp. In the case of the CAS group, the organisms were Parabacteroides spp., Blautia spp., Enterobacteriaceae spp., Turicibacter spp., species from Christenellaceae, species from Alphaproteobacteria and Mogibacteriaceae, Coprobacillus spp. and Dorea spp. In the case of the LPI group, the organisms were Lactobacillus spp. (Lactobacillus spp. and L. reuteri), species from Clostridiaceae, species from Peptostreptococcaceae, species from Erysipelotrichaceae, and Adlercreutzia spp. Conclusions: Based on the results obtained, LPI is likely to beneficially modulate the intestinal microbiota composition in rats. Additionally, LA-based diet was associated to a healthier microbiota composition than CAS, although the CAS diet also modulated the intestinal microbiota to a composition compatible with improved bowel movement frequency and lipid metabolism.