Characterization of Bacteria, Clostridia and<i> Bacteroides</i> in Faeces of Vegetarians Using qPCR and PCR-DGGE Fingerprinting

Abstract

Background/Aims: This study aimed to investigate the quantitative and qualitative changes of bacteria, Bacteroides, Bifidobacterium and Clostridium cluster IV in faecal microbiota associated with a vegetarian diet. Methods: Bacterial abundances were measured in faecal samples of 15 vegetarians and 14 omnivores using quantitative PCR. Diversity was assessed with PCR-DGGE fingerprinting, principal component analysis (PCA) and Shannon diversity index. Results: Vegetarians had a 12% higher abundance of bacterial DNA than omnivores, a tendency for less Clostridium cluster IV (31.86 ± 17.00%; 36.64 ± 14.22%) and higher abundance of Bacteroides (23.93 ± 10.35%; 21.26 ± 8.05%), which were not significant due to high interindividual variations. PCA suggested a grouping of bacteria and members of Clostridium cluster IV. Two bands appeared significantly more frequently in omnivores than in vegetarians (p < 0.005 and p < 0.022). One was identified as Faecalibacterium sp. and the other was 97.9% similar to the uncultured gut bacteriumDQ793301. Conclusions: A vegetarian diet affects the intestinal microbiota, especially by decreasing the amount and changing the diversity of Clostridium cluster IV. It remains to be determined how these shifts might affect the host metabolism and disease risks.

Beneficial modulation of the gut microbiota

“…Interestingly, the respective diets brought about a transcriptional response among the gut microbiota that was consistent with previously reported differences in gene abundances between herbivorous and carnivorous animals [61]. In other studies, members of the Clostridium clusters IV and XIVa have been found to be enriched in the faeces of omnivores compared to vegetarians and lactovegetarians, who generally consume higher proportions of carbohydrates as part of their diet [97][98][99]. These clusters of bacteria are noted for their ability to convert dietary fibre to SCFAs.…”

“…Associated with Prevotella-rich enterotype [62] Faster gut transit time compared to high protein and animal fat diet [62] Omnivorous compared to vegetarian and lactovegetarian [97][98][99] Increased Clostridium clusters IV and XIVa [97][98][99] Not reported High-fat, simple carbohydrate ''Western'' diet [38,40] Increased Firmicutes, decreased Bacteroidetes [38,40] Diet-induced obesity. Subsequent transplantation of obese microbiota to germ free mice increased adiposity [40] Reduced carbohydrate intake [63] Reduced Bifidobacterium, Roseburia spp.…”

Association of dietary patterns with the fecal microbiota in Korean adolescents

“…In our study, traditional diets comprised predominantly plantbased and fermented foods, which are low in fat and rich in carbohydrate, plant protein, vitamin, mineral, and fiber; in contrast, modified Western diets comprised greater proportions of animal-based foods and were high in fat and low in fiber. In support, previous studies have reported that vegetarian diets were associated with Bacteroides [11], and fat-restricted diets, together with higher carbohydrate intake, were linked to increased proportions of Bacteroides and Bifidobacterium [30]. However, Cani et al reported a reduction in Clostridium cluster XIVa and lower Bifidobacterium and Bacteroides levels [31] and Kim et al found the enrichment of Ruminococcaceae [32] in mice fed a high-fat diet.…”

“…Of these, diet is considered a key contributor to the diversity of the gut microbiota, explaining 57% of the total structural variation, while only 12% is related to genetic differences [10]. Therefore, many studies have focused on the relationship between the gut microbiota and dietary factors, such as dietary pattern (vegetarian and Western) [11,12], specific foods (whole grain products, fruits, and vegetables) [13][14][15][16][17], and food constituents (dietary fiber, fat, and protein) [8,[18][19][20]. Interestingly, a recent study showed that European children who consumed a typical Western diet had a microbiota enriched in Firmicutes and Enterobacteriaceae, whereas rural African children, who consumed a diet low in fat and animal protein and rich in plant-based foods, had greater abundances of the genera Bacteroidetes and Prevotella [7].…”

Intestinal microbiota and its relationship with diabetes and obesity

“…The above-described relationship is confirmed by a study of intestinal microflora in subjects on a vegetarian diet. The study demonstrated the decrease in the number and changes in the diversity of bacteria of the genus Clostridium and the increase in the number of Bacteroidetes [9]. However, researchers' opinions are divergent and not all studies have found similar correlations.…”