INCREASED RESISTANCE OF ESCHERICHIA-COLI TO ACRYLIC-ACID AND TO COPPER IONS AFTER COLD-SHOCK

The effects of cold-shock on the resistance of plasmid-free and plasmi d-carrying Escherichia coli to acrylate and copper ions have been test ed. Such shock, produced by transfer from 37 to 5 degrees C, with 60 m in incubation at the lower temperature, significantly enhanced the res istance of all the tested strains to both inhibitors. Such resistances may have arisen because the inhibitory agents are less able, due to p orin changes, to penetrate into the organisms after cold-shock. It is more likely, however, that inhibitor penetration is unaffected but tha t cold-shocked organisms are better able to repair the damage caused ( e.g. to membranes, DNA or cellular enzymes) by the inhibitors.