FIG 6.

Phylogenetic tree of Lactobacillus DdlA homologs. We constructed a phylogenetic tree based on Ddl sequences derived from 173 Lactobacillus species to predict the vancomycin resistance profile and, thus, the applicability of Ddl as a CSM. Eighty-one percent of Lactobacillus species contain a phenylalanine in the Ddl active site (blue ring), which predicts their intrinsic vancomycin resistance (Van^r). The remaining species contain a tyrosine in the active site (yellow ring), which predicts vancomycin sensitivity (Van^s). Our prediction is in accordance with established vancomycin resistance profiles (33–36).