File:Influence of Na2S concentration on M. millerae SM9 growth.jpg

The growth of M. millerae SM9 showed robust growth at intermediate Na2S concentrations of 0.4-1 mM (Fig. 3A). Cultures exhibited limited growth at 0, 0.1, or 0.2 mM Na2S, reaching a maximal OD600 of ~0.8. At higher Na2S concentrations of 2 or 4 mM, strain SM9 also grew well, although dark precipitates formed in the medium before inoculation (Fig. 3B). Therefore, high levels of sulfide did not appear to be toxic. Intermediate concentrations of Na2S (0.4-1 mM) supported robust growth without precipitate formation, indicating that this range is appropriate for growth under normal conditions.