ABSTRACT
Bifidobacteria are Gram-positive, strictly anaerobic rods, which do not reduce nitrate; are nonspore-forming; do not produce catalase; and can ferment lactose, glucose, galactose, and fructose with the production of acetic and lactic acids in an approximate ratio of 1.5:1 without the evolution of gas. All bifidobacteria contain fructose-6-phosphate phosphoketolase. The discovery of bifidobacteria may be traced to the work of Tissier, which appeared in print in 1899. Two important investigations on the lactobacilli, which provided useful information on the bifidobacteria as well, were carried out by Briggs and Sharpe. As various investigators isolated ever-increasing numbers of bifidobacterial strains from diverse sources, it became necessary to devise unambiguous methods to identify these organisms in terms of known species, or to pronounce a group of isolates as a new species. Additional taxonomic methodologies have been applied to bifidobacteria.
