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

<i>Background/Aims:</i> This study aimed to investigate the quantitative and qualitative changes of bacteria, <i>Bacteroides</i>, <i>Bifidobacterium</i> and <i>Clostridium</i> cluster IV in faecal microbiota associated with a vegetarian diet. <i>Methods:</i> 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. <i>Results:</i> Vegetarians had a 12% higher abundance of bacterial DNA than omnivores, a tendency for less <i>Clostridium </i>cluster IV (31.86 ± 17.00%; 36.64 ± 14.22%) and higher abundance of <i>Bacteroides</i> (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 <i>Clostridium </i>cluster IV. Two bands appeared significantly more frequently in omnivores than in vegetarians (p < 0.005 and p < 0.022). One was identified as <i>Faecalibacterium</i> sp. and the other was 97.9% similar to the uncultured gut bacteriumDQ793301. <i>Conclusions:</i> A vegetarian diet affects the intestinal microbiota, especially by decreasing the amount and changing the diversity of <i>Clostridium </i>cluster IV. It remains to be determined how these shifts might affect the host metabolism and disease risks.