ИСТИНА

Bacteriolytic enzymes cause the lysis of bacterial cells due to cleavage of cell wall components and are considered as potential alternative antibiotics. Not only enzymes can act as bacteriolytic agents. We showed recently, that such activity demonstrates interleukin-2 – one of the key cytokines, which is used for therapy of sepsis and oncology. Once a possible bacteriolytic agent has been identified, quantitative description of its specificity toward different types of microorganisms is essential to determine its potential as therapeutic agent. The simplest method for determination of lysis rate is turbidimetry, based on decreasing of cell suspension turbidity at 500–650 nm during cell destruction under the action of bacteriolytic agent. Usually, enzyme activity is expressed as reducing of optical density at initial time (dD/dt)o. At the same time direct comparative analysis of enzyme specificity to different microorganisms measured by turbidimetry is very complicated. First, at the same Do substrate concentration (CFU/ml) can varied 2–3 orders in dependence of cells size and form and microorganism type. Second, complete lysis according to microbiological method not always leads to the totally transparent suspension, i.e. (dD/dt)o value is not identical to the real rate of enzymatic cell lysis, (dCFU/dt)o. Mathematical analysis allowed us to find necessary conditions for transfer turbidimetrically determined rate of cell lysis to the real one. They are cell concentration CFUo at initial Do and final density D∞ when lysis is finished according microbiology – these two coefficients must be determined for the specific type of microorganism. Having a common methodological basis for action of bacteriolytic factors on cells we made a detailing comparison of lysozyme and interleukin- 2 specificity toward different bacteria types. The work was supported by Russian Science Foundation (project No. 15-14-00012 “Investigation of bacteriolytic characteristics of interleukin-2”).