title: The effect of osmotic shock on the accessibility of the murein layer of exponentially growing Escherichia coli to lysozyme.
abstract: The restricted access of lysozyme to the murein layer of exponential phase Escherichia coli is enhanced considerably by osmotic shock. When cells suspended in Tris/EDTA/sucrose are diluted 11-fold in water or 10 mM EDTA in the presence of lysozyme, their susceptibility to lysozyme increases by a factor of 50--100, for both Escherichia coli JC411 and W3110, grown to the early exponential phase in unsuppleneted or supplemented minimal media, and in Brain Heart Infusion. Since an 11-fold dilution causes lysis of lysozyme spheroplasts, the effects of  a 2-fold dilution have also been investigated. A 2-fold dilution of cell suspended in TrisEDTA/sucrose still increases their susceptibility to lysozyme by a factor of 10--50, but the resulting spheroplasts remain intact. EDTA is necessary to permit lysozyme access to the murein layer during the dilution, which is ineffective in the presence of 5 mM MgCl2. These results are discussed in terms of the formation of lysozyme spheroplasts from young Escherichia coli.
mesh_terms: D001433:Bacteriolysis; D002473:Cell Wall; D004926:Escherichia coli / Q000254:growth & development; D007700:Kinetics; D009113:Muramidase / Q000378:metabolism*; D009997:Osmotic Pressure; D010457:Peptidoglycan / Q000378:metabolism*; D013045:Species Specificity; D013104:Spheroplasts
chemical_list: D010457:Peptidoglycan; D009113:Muramidase