An attempt to cultivate mycobacteria in simple synthetic liquid medium containing lecithin-cholesterol liposomes

An attempt was made to cultivate mycobacteria in a simple synthetic liquid medium containing lecithin-cholesterol liposomes. This lipid complex showed a marked growth-promoting effect on the submerged growth of M. tuberculosis and M. bovis. The role of lecithin as nutrient was suggested. The bacillary growth in such environment retained good viability, strong acid-fastness, and high virulence in mice. An avirulent strain of tubercle bacilli, H37Ra, did not respond to lecithin-cholesterol liposomes unlike the parent virulent strain, H37Rv. However, this was not a general rule for virulence, as a highly virulent strain of M. bovis (Ravenel) and an attenuated strain (BCG) both grew well in the presence of lipsomes. Lipid analysis showed that cholesterol in the liposome medium was esterified to some extent during the bacterial growth. It was discussed that the culture in the liposome-containing medium may present an experimental model for the study of interaction between mycobacteria and the macrophage membrane.