[Various approaches to studying molecular-genetic mechanisms of low-temperature adaptation of microbial populations]

The effect of biologically low temperature (12 degrees C) on the parameters of microbial population such as survival, catalase activity and its isoenzyme spectrum have been investigated on the models of Escherichia coli and Yersinia pseudotuberculosis. The quantity of nucleic acids, plasmid spectrum and temperature effect on the level of plasmid DNA spiralization were studied under these conditions. The process of molecular genetic adaptation of bacterial populations having the broad temperature limits of growth and demonstrating the increased genetical expression when affected by the biologically low temperature has been found to be regulated on the transcriptional level. The inducible catalase isoenzymes participate in adaptation. The effect of biologically low temperature on the level of the plasmid DNA superhelicity and DNA quantity during the short period of poststress was not demonstrated.