Characterization of Bacteroides gingivalis by direct fluorescent antibody staining and cellular fatty acid profiles

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Abstract
B. gingivalis is a newly proposed species which includes strains isolated from the [human] mouth. Thirteen strains of B. gingivalis isolated from 3 geographic locations in the USA and France were examined with direct fluorescent antibody staining and analysis of total cellular fatty acids and compared with 16 strains of B. asaccharolyticus of nonoral origin by the same methods. B. gingivalis strains reacted with the B. gingivalis conjugate (fluorescein isothiocyanate labeled antibody reagent) only, while the B. asaccharolyticus strains reacted with the B. asaccharolyticus conjugate only. The B. gingivalis strains showed negative fluorescence with fluorescein isothiocyanate conjugates for other black-pigmented Bacteroides spp. The specificity of the B. gingivalis conjugate was demonstrated by its failure to stain 88 strains of aerobic and anaerobic bacteria other than B. gingivalis. The fatty acid profiles of B. gingivalis and B. asaccharolyticus were readily distinguishable. The B. gingivalis profile was also distinguishable from those of other pigmenting Bacteroides spp. on the basis of concentration ratios among the characteristic components. These results support the species separation of B. gingivalis and B. asaccharolyticus. They indicate the usefulness of cellular fatty acid profiles as an adjunct to the use of specific fluorescent antibody conjugates for identification of Bacteroides spp.