Detection of fructose-6-phosphate phosphoketolase (F6PPK), a key enzyme of the bifid-shunt, in Gardnerella vaginalis

The detection of Fructose-6-phosphate phosphoketolase (F6PPK) in cellular extracts, is considered to be the most reliable indication that Gram-positive rod-shaped bacteria belong to the genus Bifidobacterium. Recent phylogenetic studies using 16S rRNA sequencing highlighted the close taxonomic relationship between the species Gardnerella vaginalis and a group containing most of the Bifidobacterium species. In order to further investigate this relationship, we have searched for F6PPK activity in strains identified as 'true' G. vaginalis and in other catalase-negative coryneform bacteria, recently described as Actinomyces turicensis-like. Our data show that (i) the enzyme is only present in the G. vaginalis sensu stricto strains (ii) F6PPK can be considered as a taxonomic criterion of both Bifidobacterium and G. vaginalis strains, and not as the specific enzyme of the 'Bifid-shunt'. (C) 1996 Academic Press