The nutritional requirements of dysgonic and eugonic bovine tubercle bacilli were investigated in liquid Tween-albumin medium. The following conclusions were reached:—

Dysgonic bovine tubercle bacilli require for multiplication long chain fatty acids which can be supplied as oleic, palmitic, or stearic acid whereas eugonic bovine strains can grow in the absence of fatty acid and can utilize glucose as a sufficient source of carbon.

In the presence of fatty acids, the growth of dysgonic strains is increased by the addition of small amounts of glucose or glycerol, whereas large amounts of glucose or glycerol decrease the total growth and inhibit or retard the growth of small inocula.

In glucose-fatty acid media, the growth of dysgonic strains is further stimulated by the addition of sodium glutamate, succinate, malate, or acetate.

Sodium pyruvate enables dysgonic strains to grow rapidly in liquid media containing glucose or glycerol even in the absence of fatty acid.

The significance of these findings for the mechanism of the variation from "dysgonic" to "eugonic" is discussed.

The use of oleic acid-albumin agar without glucose permits the rapid isolation of bovine tubercle bacilli from natural sources.

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