Development of a real-time PCR method for Firmicutes and Bacteroidetes in faeces and its application to quantify intestinal population of obese and lean pigs.

To investigate whether the relative abundance of the Bacteroidetes and Firmicutes divisions in pigs is different between obese and lean animals. Group-specific primers were designed to target the 16S rRNA genes of Bacteroidetes and Firmicutes present in the gut. After the validation of their specificity, these primers were used in the real-time PCR quantification of all Bacteria, Firmicutes division, Bacteroidetes division and Bacteroides spp. in the faecal samples of obese and lean pigs from Banna mini-pig inbred line. The obese pigs had a approximately 61% fewer percentage (based on all Bacteria) of Bacteroidetes division (P = 0.033) and a approximately 56% fewer proportion of Bacteroides spp. (P = 0.047) than the lean pigs. The proportions of both Bacteroidetes and Bacteroides had a negative correlation (P < 0.01) with the body weight. The results suggested that the fat storage might affect the proportion of Bacteroidetes division in the gut. The real-time PCR assays developed for Firmicutes and Bacteroidetes will be useful for investigating the composition of gut microbiota.