The effect of metal chelators and other metabolic inhibitors on the growth of Bifidobacterium bifidus var. Pennsylvanicus.

Bifidobacterium bifidus var. Pennsylvanicus, a microaerophilic anaerobe, was grown in the presence of several potential growth inhibitors with the aim of defining its growth requirements and metabolic peculiarities. The following had no effect on its growth: citrate, serum transferrin, serum albumin, colchicine, fluoro-acetate, malonate, and rotenone. The following substances inhibited the growth: fluoride, azide, arsenite, 2, 4-dinitrophenol, hemin, hemoglobin, lactoferrin, alpha, alpha'-bipyridyl, and 8-hydroxyquinoline. Ferrous iron was able to negate the inhibition achieved by alpha, alpha'-bipyridyl, and 8-hydroxyquinoline. It is concluded that iron, probably in its ferrous state, is an obligatory nutrient for the microorganism, and that iron-porphyrin system(s) may be essential for the metabolism of this organism. Because the microorganisms contained in addition to iron large quantities of Mn, Zn, and Cu, it is likely that these metalloelements are crucial for the normal growth of the organism. Growth inhibition by fluoride indicates that Mg-dependent enzymes may also be present in the microorganism.