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Detection, cellular localization and antibacterial activity of two lytic enzymes of Pediococcus acidilactici ATCC 8042
- GarcÃaâCano, I., VelascoâPÃ©rez, L., RodrÃguezâSanoja, R., SÃ¡nchez, S., MendozaâHernÃ¡ndez, G., LlorenteâBousquets, A., FarrÃ©s, A.
- Journal of applied microbiology 2011 v.111 no.3 pp. 607-615
- Bacillus cereus, Escherichia coli, Gram-positive bacteria, Listeria monocytogenes, Micrococcus luteus, N-acetylmuramoyl-L-alanine amidase, Pediococcus acidilactici, Salmonella typhimurium, Staphylococcus aureus, antibacterial properties, cell membranes, developmental stages, fermented foods, genome, lactic acid bacteria, manufacturing, mass spectrometry, minimum inhibitory concentration, polyacrylamide gel electrophoresis, proteins, virulent strains
- Aim: In Pediococcus acidilactici ATCC 8042, two activities of peptidoglycan hydrolase (PGH) with lytic effect against Micrococcus lysodeikticus and Staphylococcus aureus have been detected. This work intends to elucidate the growth phase of maximum lytic activity, the localization and the effectiveness of the activity against pathogenic Gramânegative and Gramâpositive bacteria. Methods and Results: Cells were grown in MRS medium and collected at different growth stages, and the proteins were extracted. The highest PGH activity was found during the logarithmic growth phase in the protein fraction bound to the cell membrane. From this fraction, two distinct proteins bands (110â and 99âkDa) in SDSâPAGE were partially purified with a threeâstep procedure. Both bands showed lytic activity against M.Â lysodeikticus. Mass spectrometry analysis (LC/ESIâMS/MS) indicated that the 110âkDa band corresponded to a protein of unknown function. The 99âkDa band corresponded to a Nâacetylmuramidase that harboured catalytic sites with Nâacetylmuramoylâlâalanine amidase and Nâacetylglucosaminidase activities. Both proteins are reported in the Ped.Â acidilactici 7_4 genome. The fraction containing the concentrated proteins (110 and 99âkDa) inhibited the growth of several pathogenic strains as: Bacillus cereus, Listeria monocytogenes and Salmonella typhimurium. The growth of S.Â aureus was diminished by 3 logarithmic units as early as 0Â·5âh of growth, while inhibition of Escherichia coli and Ped.Â acidilactici was observed after 18 and 8âh, respectively (both in one logarithmic unit). The minimum inhibitory concentration against S.Â aureus was 10âÎ¼gâmlâ1. Conclusion: Pediococcus acidilactici harbours at least two lytic enzymes, one of them recognized as PGH for the first time, which exert antibacterial activity against several bacterial strains. Significance and Impact of the Study: Both PGH activities have a broad growth inhibition spectrum and could be used to control pathogenic bacteria. Because this activity comes from a lactic acid bacterium, it could be safely used in manufacturing processes of fermented foods.