DEATH OF ESCHERICHIA COLI FROZEN ON CELLOPHANE AND ON MEMBRANE FILTERS

Abstract

Because Escherichia coli stored at −9 °C on cellophane or membrane filter disks die similarly to cells in frozen suspensions, it seems unlikely that mechanical crushing or concentrated solute is responsible for the major part of freezing death. Increased survival of high concentrations of cells regardless of the method of storing implies an interaction between cells prior to freezing. The age of the cells plays a part. The results may be interpreted in terms of an exchange or loss of stimulatory or inhibitory substances in small amounts from individual cells either before or after frozen storage.