[Optimization of lysozyme determination: comparative study of preparations of test cultures of Micrococcus luteus (M. lysodeikticus Fleming)].

About 6000 single measurements of the susceptibility of different preparations of Micrococcus luteus (M. lysodeikticus Fleming) cells were performed in order to assess their suitability for the determination of various muramidase concentrations. In particular, a turbidimetric method was compared with an agar-diffusion technique under varying experimental conditions. From our results it can be concluded that M. luteus cells washed with ether and acetone or living lyophilized cells are most suitable for turbidimetric determinations of lysozyme activity. The optimum conditions for turbidimetric assays comprised an initial transmission of 20% and a test time of 5 min. For the agar-diffusion technique fresh living or living lyophilized cells were most suitable. For a given incubation time of 3 h an incubation temperature of 50 degrees C yielded the best results.