A study into measuring the antibacterial activity of lysozyme‐containing foods

Abstract

PurposeThe purpose of this paper is to provide food science or biology students with a simple and reliable method of determining the antibacterial activity of a range of foods and biological materials that contain lysozyme.Design/methodology/approachThe antibacterial effects of the materials reported to contain lysozyme were assayed by gel‐diffusion using the lysozyme‐sensitive bacterium Micrococcus lysodeikticus. The antibacterial effects of the selected test materials, namely fresh hen egg‐white, human saliva, Brussels sprouts, papaya and figs were compared against standard solutions of proprietary analytical crystalline hen egg‐white lysozyme.FindingsThe antibacterial activity of the test substances was similar to the effects of their lysozyme concentrations as quoted by other workers.Research limitations/implicationsAntibacterial activity was higher in avian egg‐white and human saliva than in the assayed plant material. Measurement of the activity in the plant material was at the limits of the sensitivity of the method.Practical implicationsThe two main practical methods for measuring lysozyme are either a gel‐diffusion assay or a spectrophotometric procedure. Gel‐diffusion assay provides a convenient procedure for student investigative work as it has a limited requirement for method development. Additionally, it is simple, cheap, reproducible and does not require specialist equipment. Further possible investigations for students are suggested.Originality/valueThe paper builds on established techniques to provide a procedure that is appropriate for student use for determining lysozyme activity in a variety of biological materials.