Single-cell enumeration of an uncultivated TM7 subgroup in the human subgingival crevice

Specific oligonucleotide hybridization conditions were established for single-cell enumeration of uncultivated TM7 and 1025 bacteria by using clones expressing heterologous 16S rRNA. In situ analysis of human subgingival crevice specimens revealed that a greater proportion of samples from sites of chronic periodontitis than from healthy sites contained TM7 subgroup IO25. In addition, 1025 bacterial cells from periodontitis site samples were more abundant and fourfold longer than IO25 cells from healthy site samples.