title: Transition temperatures in the sensitivity of Escherichia coli B/r to lysozyme.
abstract: Lysozyme attacked Escherichia coli B/r in the absence of EDTA or imposed osmotic shocks when the cells were rapidly cooled below specific temperatures. Cells subjected to lysozyme while being cooled to below 20 degrees C began to lose ability to subsequently form colonies. This sensitivity increased with decreasing temperatures and almost all cells cooled to 0 degrees C were affected. Slightly hypertonic solutions did not improve survival. Cells cooled first to as low as 5 degrees C and then subjected to lysozyme while cool did not lose their ability to form colonies subsequent to rewarming. However, 70% of the cells cooled first to 0 degrees C and subjected to lysozyme lost their colony-forming ability. Cell lysis also began when treated near 5 degrees C, but even when treated at 0 degrees C about 50% of the cells maintained their rod shape in the presence of lysozyme. These results are discussed in terms of a possible phase transition in a portion of the cell envelope and/or a transient osmotic swelling as a results of metabolic pumps failing at the low temperatures.
mesh_terms: D004492:Edetic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D007700:Kinetics; D009113:Muramidase / Q000494:pharmacology*; D013696:Temperature
chemical_list: D004492:Edetic Acid; D009113:Muramidase