Antimicrobial activity of several bis-methanethiolsulfonates.

We determined the inhibitory end point of a series of bis-methanethiolsulfonates, CH(3)SO(2)S(CH(2))(n)SSO(2)CH(3) (n = 2 to 6), and correlated the structures with antimicrobial activity. Eleven microorganisms were used in the evaluation, and the maximal activity occurred when the methylene chain length was five or six. The effect of CH(3)SO(2)S(CH(2))(5)SSO(2)CH(3) (PMTS) on respiration of Aerobacter aerogenes and Staphylococcus aureus was studied at various stages of their growth cycles. The effect on viability was correlated with that of respiration in the case of A. aerogenes. Respiratory inhibition caused by PMTS varied with the growth phase of both organisms, being most pronounced when the cells tested were taken during the period of transition from the log to stationary phase. The lethal effect on A. aerogenes was also greatest at this time. During the period of increased sensitivity, the antimicrobial activity of PMTS appears to be closely related to cell respiration. The delayed rate of kill otherwise observed may reflect an impairment of protein metabolism through reaction with sensitive SH groups.