In vitro growth of Mycobacterium lepraemurium, an obligate intracellular microbe

By using an ultrasensitive technique to measure adenosine triphosphate in terms of functional biomass, we have confirmed that Mycobacterium lepraemurium (the agent of rat leprosy and a classical obligate intracellular microbe) grows in vitro in the Nakamura system. By using a sulfhydryl-containing medium that ocupies 65 to 75% of the culture tube volume, together with the five supplements recommended by Nakamura, we have obtained growth rates some eight times above the original. The new physicochemical environment and the use of adenosine triphosphate as an index of energy status in the presence and absence of growth provide a basis for investigating the physiology and growth of other noncultivated microbes.