Comparative aspects on the determination of lytic activity in lysozyme

Abstract

Lysozyme is a bacteriolytic enzyme found in milk of a large number of mammalian species. Its determination is useful in medicine, veterinary and experimental biology. The present study shows the usual method of measurement using bacterial lysis, the turbidimetric method, presenting intrinsic problems making its use inadequate. Assays of lysozyme activity were carried out in milk of three mammalian species (tapir, southern sea lion, and human) using different dilutions. It was shown that lytic values were not proportional to lysozyme concentration over time, neither to lytic effects extrapolated to the first second of incubation. Moreover it was shown that after a certain incubation time, and lysis, and in spite of non damaged bacteria, a great part of the lysosyme was not found united to bacteria but in the supernatant liquid. The lack of correlation between lysozyme concentration and lytic effects over time make the turbidimetric method non recommendable for measuring lysosyme activity for comparative and referential purposes.