The Influence of Foodstuffs upon the Respiratory Metabolism and Growth of Human Tubercle Bacilli

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Abstract
The H37 strain, studied in Warburg''s microrespiration apparatus, consumed O at a rate comparable to that of mammalian cells. Glycerol causes the highest O consumption. However, for purposes of oxidation this can be replaced by Na lactate, Na salts of higher fatty acids, and diluted blood serum or caseous material (some about as effective as glycerol). Lecithin, milk, and serum fat fall in the same category; smaller effects are observed with glucose and glycogen. For respiration, it is not necessary that these substances be present in concentrations required for abundant growth. Stimulation of respiration by glycerol is perceptible at 0.005% and by Na lactate in nearly as weak a solution. The effect of soap is very marked at 0.1%; milk fat at this dilution seems to produce detectable stimulation. Both glucose and lactate are effective in concentrations at which they occur normally in blood. These observations explain how it may be possible for tubercle bacilli to obtain energy from the circulating blood at concentrations of various foodstuffs which in media may be unable to support rich growths. The role of white blood cells in supplying the bacteria with foodstuffs has been only suggested. Glycogen and lactate might be more readily furnished by monocytes, for instance, than by circulating blood. Caseous material contains several ingredients, each of which can support a high level of respiration by the H37 strain. In fact, with this material there was evidence of adequate food supply and no toxic effect on respiration for several hrs.