Development of a Colorimetric Method for Lysozyme Assay Using Methylene Blue as the Cell Wall Binding Agent

Abstract: The potential of lysozyme to degrade bacterial cell wall has found important applications in the fields of medicine and biotechnology. The ability of methylene blue dye to bind to the cell walls of bacteria was utilized for development of an assay method for measurement of lysozyme activity. The method was calibrated with the commercial preparation of lysozyme using Micrococcus lysodeikticus cells as substrate. The method was functional over a range of 5–40 U/mL. The method was compared with the conventional turbidimetric method. Sensitivity of the method was similar to turbidimetric method as both the methods could detect lysozyme activity as low as 5 U/mL. Enzyme activity in saliva samples measured by both the methods was comparable and ranged from 1000 to 2100 U/mL.