FIG. 4.

Phylogenetic tree of the phylum Firmicutes identified from clone libraries. The phylum Firmicutes is presently divided into three classes: “Bacilli,” Mollicutes, and “Clostridia.” This phylum represented the largest group detected; 115 species or novel phylotypes were identified (Table 4). Streptococcus oralis and S. mitis could not be differentiated based on sequence comparisons. Consequently, the two species are grouped together. The marker bar represents a 5% difference in nucleotide sequences.