Figure 5.

LMWT and LMW persulfide metabolite profiling of Vibrio cholerae strains. A, cartoon representation of the scheme for LMWT and LMW persulfide profiling. Growth of a ΔCTX Vibrio cholerae strain until A of ∼0.2 is followed by the addition of Na₂S or H₂O₂ to a final concentration of 0.2 mM. Cultures were centrifuged at 0 (prior to addition of the stressor), 15, 30, and 60 min. In all cases 1 ml of sample was withdrawn for protein quantitation. The metabolite profiling was generally carried out using HPE-IAM as labeling agent. The ratiometric LC-ESI-MS experiments were performed with the dilution of isotopically labeled internal standards of known concentration, which were used for quantitation of the organic and inorganic species. B, endogenous concentrations of hydrogen sulfide before and after addition of stress (Na₂S, red; H₂O₂, blue) to midlog-phase cultures. C, endogenous concentrations of hydrogen disulfide before and after addition of stress (Na₂S, red; H₂O₂, blue) to midlog-phase cultures. D, endogenous concentrations of CysSSH, GSSH, and h-CysSSH before and after addition of stress at different timepoints to midlog-phase cultures. Statistical significance was established using a paired t test relative to UN under the same conditions (∗∗p < 0.01, ∗p < 0.05). HPE, β-hydroxyphenyl-ethyl; IAM, iodoacetamide.