The Biology of the Tubercle Bacillus

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Abstract
2 strains of tubercle bacilli were employed,[long dash]virulent H 37 and avirulent H 520. These seemed to be alike in their metabolism on the synthetic medium employed, except that the avirulent bacilli grew more rapidly and produced a terminal alkalinity, while the virulent form grew more slowly and produced a terminal acidity. The titratable reaction and pH curves closely paralleled each other throughout the exp. Apparently, there was no relationship between titratable alkalinity and NH3. The NH3 content of the medium for both organisms was small, but showed a maximum at time of greatest growth, followed by a recession. This would indicate that the alkalinity produced in the H 520 medium was not due to NH3. N determinations showed that practically all the N of the asparagin was utilized by both organisms. Glycerol was practically completely utilized by both organisms, the decrease in amount in the medium occurring much more rapidly with H 520 than with H 37. It appeared likely that utilization was complete and that glycerol was not partially oxidized to organic acids. The acidity produced in the medium seemed to a considerable extent to be due to metabolism of asparagin. The terminal alkalinity produced by the avirulent form may be explained by the assumption that there occurred further utilization of acidic compounds produced from the asparagin.