| Abstract [eng] |
We used potenciometric measurments to investigate the response of Gram-positive and Gram-negative bacteria to cell envelope stress, caused by native and heat-inactivated lysozyme and lysozyme-derived 9 amino acid peptide. It was found that these antimicrobial compounds induce leakage of K+ outside the cells of L. lactis, B. subtilis and P. aeruginosa and cause partial depolarization of bacterial cytoplasmic membrane. We observed different response of L. lactis cells to these compounds – peptide and heat-inactivated lysozyme cause more rapid efflux of K+ ions than native lysozyme. Peptide has a reversible effect on K+ leakage. Sensitivity of different mutant strains of L. lactis to lysozyme was studied. It was shown that more resistant the strain is, the later the leakage of K+ ions is induced by lysozyme. To investigate the genome-wide response of L. lactis MG1363 and ΔoppA strains to lysozyme and 9 a.a. peptide, changes of gene expression after challenging cells with these antimicrobial compounds were analysed using DNA microarrays. It was estimated, that lysozyme and lysozyme-derived 9a.a. peptide induce CesSR system and SpxB-mediated response. It was also shown that L. lactis response to 9a.a. peptide and lysozyme differs. Lysozyme specifically induces PgdA-mediated resistance mechanism. Changes of expression of OpuA system in lysozyme and peptide treated cells are also different. |
