Ratledge C, Hall M J
J Bacteriol. 1971 Oct;108(1):314-9. doi: 10.1128/jb.108.1.314-319.1971.
Mycobacterium smegmatis was grown on trace-metal-free medium in static culture. Throughout the growth phase, the concentration of mycobactin increased continuously, reaching a maximum of about 30 to 40 mug of mycobactin/mg of cell dry weight after 6 days; the concentration of salicylic acid remained approximately constant at 1 to 2 mug of salicylic acid/mug of cell dry weight. Fe(2+) (or Fe(3+)), Zn(2+), Mn(2+), and Mg(2+) were all essential to a maximum formation of mycobactin. Optimum concentrations required were: Fe(2+), about 1.8 mum; Mn(2+) and Zn(2+), about 0.5 mum; and Mg(2+), at least 0.17 mm. Higher levels of Fe(2+) (9 to 90 mum) and Zn(2+) (2 to 7 mum) repressed mycobactin to about half the maximum value. No other cation or anion apparently is required for mycobactin biosynthesis. Salicylic acid concentration increased about fourfold when iron was omitted from the medium, but this is not as great as the increase reported previously for this strain of M. smegmatis. Mycobactin formation in another strain of M. smegmatis, NCIB 8548, showed similar dependencies on Fe(2+), Zn(2+), and Mn(2+). Maximum accumulation of mycobactin with this strain was 85 mug of mycobactin/mg of dry cell weight, under iron-deficient (1.8 mum Fe(2+)) conditions.
耻垢分枝杆菌在无微量元素的培养基中静置培养。在整个生长阶段，分枝杆菌素的浓度持续增加，6天后达到最大值，约为30至40微克分枝杆菌素/毫克细胞干重；水杨酸的浓度保持在约1至2微克水杨酸/微克细胞干重相对稳定。Fe(2+)（或Fe(3+)）、Zn(2+)、Mn(2+)和Mg(2+)对分枝杆菌素的最大合成均至关重要。所需的最佳浓度为：Fe(2+)约1.8微摩尔；Mn(2+)和Zn(2+)约0.5微摩尔；Mg(2+)至少0.17毫摩尔。较高水平的Fe(2+)（9至90微摩尔）和Zn(2+)（2至7微摩尔）会使分枝杆菌素的合成抑制至最大值的一半左右。显然，分枝杆菌素生物合成不需要其他阳离子或阴离子。当培养基中不含铁时，水杨酸浓度增加约四倍，但这不如先前报道的该耻垢分枝杆菌菌株的增加幅度大。另一株耻垢分枝杆菌NCIB 8548中分枝杆菌素的形成对Fe(2+)、Zn(2+)和Mn(2+)表现出相似的依赖性。在缺铁（1.8微摩尔Fe(2+)）条件下，该菌株中分枝杆菌素的最大积累量为85微克分枝杆菌素/毫克干细胞重量。
