[Membrane potential before and after deep freezing of Escherichia coli in the presence of dimethyl sulfoxide and diethyl sulfoxide].

It was shown by the method of penetrating tetraphenylphosphonium cations that low-temperature freezing (-196 degrees C) of Escherichia coli leads to a sharp decrease (from 198 to 85 mV) in membrane potential. Incubation of bacteria in a medium containing dimethyl sulfoxide and diethyl sulfoxide as cryoprotectors results in a reduction of the potential by 16 and 27 mV, respectively. It was also shown that diethyl sulfoxide is more effective in maintaining the membrane potential after freezing--thawing than dimethyl sulfoxide.