Effect of microbial substances of different origins on the growth of Mycobacterium leprae.

Mycobacterium leprae multiplied in media enriched with substances originating from other mycobacteria, from non-acid-fast Actinomycetales or from gram-positive or gram-negative Eubacteriales. Most of the M. leprae strains did not grow on a synthetic medium containing the amino acids present in M. smegmatis, but the growth-promoting effect of sonic extracts of this organism indicated that substances of bacterial origin, other than amino acids, do act as growth factors. The identification of the growing, acid-fast microorganisms with M. leprae was verified by their ability to oxidize D-3,4-dihydroxyphenylalanine (D-dopa test). M. leprae did not multiply on Nakamura medium unless at least 40% of medium NM7 enriched by bacterial substances was present. Adequate aeration was essential for multiplication of M. leprae in enriched NM7 and No. 3 media.