Quantitative Multiplication of Mycobacterium lepraemurium in a Cell-free Liquid Medium (NC-5)

SUMMARY: Mycobacterium lepraemurium multiplies in a cell-free liquid medium, referred to as NC-5, which is enriched Kirchner medium plus goat serum, α-ketoglutaric acid, cytochrome c, haemin, and l-cysteine. At 30 °C, the bacilli gradually elongated before multiplying 100- to 1000-fold. The maximum number of bacilli is reached after 8 weeks’ incubation. The generation time of Mycobacterium lepraemurium is between 8 and 14 days, depending upon the size of inoculum. Bacilli grown in NC-5 medium maintain their capacity to produce leprosy in mice. Optimum growth was with the basal medium at pH 7·3 using a small number of bacilli in the inoculum.