[Mechanism of the metabolic death of Escherichia coli B cells following freezing and thawing].

The state of E. coli B genome after low-temperature freezing and subsequent thawing (F--T) has been studied. The study has shown that in the process of F--T the DNA of the cells remains intact. But after thawing the incubation of the cells at 37 degrees C leads to the accumulation of ruptures in their DNA and its low-molecular decomposition products. At the same time the processes of the synthesis of DNA and proteins are suppressed to a considerable extent. Repeated F--T cycles enhance, on one hand, the inhibition of the processes of synthesis and, on the other hand, the activation of DNA metabolic decomposition. Such unbalance of the competitive enzymatic systems governing the synthesis and decomposition of DNA, which appears in the process of the revival of the cell from anabiosis, leads supposedly to the accumulation of ruptures and "gaps" in its DNA and, as a result, to the fragmentation of the genome and the death of the cell.