EFFECT OF CONCENTRATION OF COMPOUNDS CONTAINING IRON ON THE GROWTH OFPORPHYROMONAS-GINGIVALIS

We examined the effect of the concentration of various types of iron m olecules on the regulation of growth of Porphyromonas gingivalis. Bact erial growth was monitored spectrophotometrically. The hemin-depleted cells of P. gingivalis 381 were incubated in the basal medium plus tes t substrates such as hemoglobin, hemin, transferrin and various inorga nic iron compounds. The relationship between the specific growth rate of organisms and the concentration of iron-containing compounds was de termined. The value of K-s, a parameter analogous to the Michaelis-Men ten constant, was estimated. P. gingivalis 381 showed a K-s value of 3 .85, 4.91 and 0.0017 mu M for hemin, transferrin and hemoglobin, respe ctively. However, the inorganic iron compounds tested did not support growth of P. gingivalis. These findings suggest that P. gingivalis uti lizes hemoglobin as an iron source much more effectively than other ir on-containing compounds under an iron-limited environment.