FIGURE 1.

IscS, not 3-MST, is the primary source of H₂S in E. coli under anaerobic conditions. (A) H₂S production in E. coli cultured under aerobic conditions. (B) H₂S production in E. coli cultured under anaerobic conditions. 3-MST activity was inhibited using 50 mM PPNa. H₂S production in E. coli cultured without PPNa was used as control group. (C) H₂S production in E. coli cultures under aerobic conditions. (D) H₂S production in E. coli cultures under anaerobic conditions. H₂S production in E. coli cultures was monitored using [Pb(NO₃)₂]-soaked paper. Saturated papers were quantified using Image Pro Plus 6.0, and the integrated optical density (IOD) value was normalized to the OD₆₀₀ value of the culture. Each bar represents the mean ± SD of four independent experiments. ^∗p < 0.1, ^∗∗∗p < 0.001, N.S., not significant, versus the control or wild-type group.