[Reasons why Mycobacterium leprae cells do not multiply under the cell-free condition]

Our previous paper reported that the intracellular ATP content in cells of M. leprae consistently increased in the medium containing adenosine after 4-6 weeks of cultivation and decreased thereafter. The reason why ATP generation ceased 4-6 weeks after cultivation is not clear, but it was determined that the termination in ATP generation was not a result of deterioration in the culture medium during cultivation because a renewal trial of the old culture medium by freshly prepared culture medium had no effect further maintenance or progressive increase in ATP generation. From the results obtained in a renewal trial of the culture medium, I would like to speculate that the reason why M. leprae cells do not multiply in vitro might be due to the characteristic property of the cell wall of M. leprae, i.e., fragility.