A Crystalline Substance isolated from Egg Yolk which promotes Growth of a Minute Inoculum of Human Tubercle Bacilli

Abstract

EGG yolk is the chief component of the solid culture media which are currently employed for the clinical detection of tubercle bacilli¹. But these egg media coagulate during their sterilization treatment and cannot liquefy again once they are so treated. This property is an essential defect in laboratory practice compared with ordinary agar solid media. So I have attempted to find the growth-supporting substance from a minute inoculum of the bacilli in the egg yolk and to add it to the agar medium which could be used as a routine agar medium for the tubercle bacilli. This substance was isolated in the crystalline form and a simple synthetic solid medium was devised which contained, a small amount of it and ‘Tween 80’ as a carbon source². This in minute amounts supported the growth of human tubercle bacilli. This communication deals with the method of isolating the crystalline substance and its principal properties and those of the synthetic agar medium containing it.