Studies on the mycolic acids from the walls of Mycobacterium microti.

Mycobacterium microti walls contained three types of mycolic acids, very similar to those found in Mycobacterium tuberculosis. An alpha-mycolate with two cyclopropane rings, a methoxymycolate with one cyclopropane ring and a methoxyl group, and a ketomycolate with one cyclopropane ring and a keto group were partially characterized. The mycolates made up 34% (by weight) of the peptidoglycan-arabinogalactan-mycolate wall skeleton. Young exponential phase cultures and organisms harvested from mouse lungs contained high proportions of ketomycolates; older cultures had roughly equal proportions of keto- and methoxymycolates. The proportion of alpha-mycolates increased slightly with age of culture, but was always less than one-third of the total.