ACID-BASE MODULATION OF LYSOZYME ACTIVITY IN MEDIUM FOR CULTIVATION OF ENTEROBACTERIA

Abstract

Aim. Determination of modulating effect of acid-base state of medium for cultivation of enterobacteria on activity of C-type lysozyme. Materials and methods. Escherichia coli BL21(DE3) strain for protein expression, Escherichia coli K12 MG1655 model strain, Escherichia coli No. 242 strain, isolated from intestine biotope; 2 Klebsiella pneumoniae strains, one of those contained plasmid homologue of periplasmatic lysozyme inhibitor gene pliC; 1 typical Salmonella enterica ATCC 14028 strain and a Micrococcus luteus ATCC 15307 strain as a control - served as material for the study. The bacteria were cultivated for 24 hours in 2 ml of liquid medium LB at 37°C, 250 rpm. Determination of antilysozyme activity (ALA) was carried out by a photonepehlometri-cal method according to O.V Bukharin et al. (1999) with alterations. Results. All the studied microorganisms, including Micrococcus luteus, at the specified conditions 24 hours after cultivation were established to change the pH of the liquid nutrient medium LB from the initial value of 6.6±0.1 to 8.2±0.2 units. ALA determination in the cultivation medium without buffer correction was accompanied by a decline of lysozyme activity at an order of magnitude. The effect was absent during ALA measurement by a standard technique. Conclusion. The local shift of acid-base state of biotope under the conditions of buffer system insufficiency results in a reversible alteration of antimicrobial activity of muramidase, that among other non-specific factors of the environment determines the background of interactions on the level of associative symbiosis. This aspect should be taken into consideration during development of models, that are close to real conditions of microsymbiocenotical interactions.

Keywords

• lysozyme
• lysozyme inhibitors
• antilysozyme activity
• enterobacteria
• bacterial persistence
• acid-based state