Identification of a component of crystalline egg albumin bactericidal for thermophilic aerobic sporeformers

During an investigation of the effect of basic and acidic proteins on the growth of thermophilic aerobic sporeformers, crystalline egg albumin was found to be strongly bactericidal. This finding was uncharacteristic of acidic proteins. The bactericidal fraction was heat sensitive and separated from the non-bactericidal albumin fraction during gel filtration on Sephadex G-75. Cells of Micrococcus lysodeikticus and Bacillus stearothermophilus were lysed rapidly by the bactericidal component, leading to its tentative identification as lysozyme. The bactericidal substance possessed an electrophoretic mobility on polyacrylamide gel containing sodium dodecyl sulfate identical to that of crystalline egg white lysozyme. Users of crystalline egg albumin are cautioned that commerical preparations may be contaminated with lysozyme. Destruction of the thermophilic aerobes by lysozyme should be considered when performing counts on egg products.