Diversity and metabolic impact of intestinalLactobacillusspecies in healthy adults and the elderly

Abstract

The present study aimed at assessing the counts and species distribution of intestinal lactobacilli and exploring if the data are associated with BMI and blood glucose level in healthy adults and elderly persons. The BMI (P < 0·01), the level of fasting blood glucose (P < 0·001) and the total counts of lactobacilli (P < 0·01 by bacteriology;P < 0·001 by real-time PCR) were higher in the elderly. The number of species in adults was lower (P < 0·05), who were more often colonised withLactobacillus acidophilus(P = 0·031) andL. helveticus(P < 0·001). In contrast,L. plantarum(P = 0·035),L. paracasei(P < 0·001) andL. reuteri(P = 0·031) were more prevalent in the elderly.L. rhamnosuswas detected in adults (P < 0·001), but not in any elderly person. BMI was associated with counts of lactobacilli, adjusted for age and sex (P = 0·008). The higher BMI in both groups of persons was associated with the presence of obligate homofermentative lactobacilli andL. sakei, both adjusted for age and sex. Plasma glucose values were positively correlated with BMI and negatively correlated with colonisation withL. paracasei(P = 0·0238) in adults and on the borderline withL. fermentum(P = 0·052) in the elderly. Thus, the species-specific PCR analysis ofLactobacillussp. combined with viable plating data indicates substantial age-related structural differences in the intestinal lactobacilli communities. The higher counts of intestinalLactobacillussp. are associated with higher BMI and blood glucose content, while their specific fermentative groups and species of lactobacilli appear at different glucose levels both in adults and in the elderly.