Quantification of Blautia wexlerae and Blautia luti in human faeces by real-time PCR using specific primers

The Clostridium coccoides group, including the genus Blautia and other genera, is one of the predominant bacterial groups in the human intestine. We re-examined 266 human faecal clones and 58 isolates in the C. coccoides group isolated by Hayashi et al. (2002) in order to elucidate the detailed distribution of Blautia wexlerae and Blautia luti in human faeces. Subsequently, we designed a primer pair specific for B. wexlerae and B. luti based on the 16S ribosomal RNA (16S rRNA) gene sequence. The number of B. wexlerae and B. luti in faecal samples of 12 healthy Japanese subjects was examined by real-time PCR assay. The number of the C. coccoides group in the 12 faecal samples was also determined using C. coccoides group-specific primers. Re-examination of the human faecal clones and isolates revealed that B. wexlerae and B. luti accounted for 19.5% of the clones and 25.9% of the isolates. B. wexlerae and B. luti were detected in all faecal samples with 5.3±3.2×10(9) cells/g faeces (wet weight, average ± standard deviation) as assessed by real-time PCR. Furthermore, B. wexlerae and B. luti constituted 32.3±12.7% (average ± standard deviation) of the C. coccoides group (1.7±0.8×10(10) cells/g faeces). This demonstrates that B. wexlerae and B. luti were presented in human faeces with a high frequency as the dominant bacteria.