CHANGES IN THE AMOUNT OF SH COMPOUNDS IN ESCHERICHIA-COLI AND BACILLUS-SUBTILIS CULTURES ON TRANSITION TO THE STATIONARY PHASE

We have established that the "jump" in the redox potential reported earlier for aerobic Escherichia coli and Bacillus subtilis cultures on transition to the stationary phase is the result of an increase in the amount of SH compounds in the medium and on the cell surface. The effect is absent in anaerobic cultures and also in aerobic E. coli cells treated with carbonyl-cyanide-m-chlorophenylhydrazone. It is believed that increase in the amount of thiols outside the cell on starvation is part of a process leading to a shift in the ratio of low molecular weight thiols to disulfides towards disulfides within the cell and towards thiols outside the cell, and is associated with the drop in intracellular pH value. Therefore the entire metabolism of the cell can change on transition of the cells to the stationary phase, due to an exchange with the main -SH groups of the functionally important compounds.