Abstract
The fact that the pneumococcus, when grown on media containing blood pigment, produces a greenish disintegration product of hemoglobin, has long been utilized as one of the means of identifying this organism. Jensen 1 states, “Pneumococci and certain streptococci produce a green pigment when grown in blood agar, and this pigment is termed methemoglobin in all text books on bacteriology. Unfortunately the literature of blood pigments is in a state far from clarified. Many European investigators do not attempt to name the particular form of blood pigment, but refer to it simply as 'a green discoloration'.”
Since the work of Conant 2 and Conant and Feiser 3 methemoglobin has been characterized as oxidized or monodelectronated reduced hemoglobin. It differs from hemoglobin only in having its iron in ferric form. Its color is definitely brownish without any element of green, and in that manner differs from the color of green hemolysis. Because of this discrepancy, an investigation was undertaken to determine the exact status of the green pigment.
Experimental. The green portions produced in pneumococcus cultures on blood agar were excised and tested for methemoglobin spectroscopically, by ammonium hydroxide, and by sodium cyanide. The differences in the effect produced by the green pigment and by methemoglobin are tabulated:
It appears therefore that the green pigment differs radically from methemoglobin. Although Neill and Hastings 4 studied the formation of methemoglobin from hemoglobin by the action of soluble extracts of pneumococcus, this does not seem to be a feature of their growth in culture.
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