Abstract
As previously reported, 1-6) the two strains of the supposed murine leprosy bacilli have been isolated and maintained on the 1% egg yolk medium incubated at 37°C.However, it is not clear whether or not this temperature is optimal for their growth. The present paper is concerned with the temperature for growth of the organisms.
The growth used for inoculation were 37 subcultures of the organisms which had been isolated from mice previously inoculated with the Hawaiian strain of M. lepraemuriumand 29 subcultures of the organisms isolated from mice with the Keishicho strain of M. lepraemurium. Each colonial growth on the egg yolk slant, 2 to 3 months old and about 2 to 4mm in diameter, was divided by loop into five or seven pieces which were then transferred to one egg slant and four or six egg yolk slants separately ; three out of them (one egg and two egg yolk slants) were incubated at 37°C and the rest were incu-bated in pairs at a lowere or higher temperature. Incubators were used at 22°, 30°, 37° 40°, and 45°C. Observations were repeated weekly or biweekly and the final reading for positive growth was made after 3 months' incubation by comparing the size of the gross visible growth on the egg yolk slant with that of the negative control growth on the egg slant at 37°C.
The results summarized in Tables 1&2 indicate that the temperature for growth of the supposed murine leprosy bacilli ranges from 30° to 37°C their temperature optimum is 37°C. In control experiments the temperature range of M. tuberculosis and M. bovis (BCG) was found to be from 30°to 40°C and that of certain sapid growers from 22°to 45°C (Tables 1&3).
These findings suggest that the two strains of the supposed murine leprosy bacilli are quite distinct from the mycobacteria used as the controls.
