Peptidoglycan Hydrolases of Probiotic Pediococcus acidilactici NCDC 252: Isolation, Physicochemical and In Silico Characterization

Abstract

Pediococcus acidilactici NCDC 252 is a Gram-positive lactic acid bacteria (LAB) that is being studied to develop it as probiotic and starter culture for dairy and meat industry. Peptidoglycan hydrolases (PGHs) are also gaining interest because of their antibacterial activity. NCDC 252 genome was searched for PGH encoded genes and product of these genes were in silico characterized for different parameters. Extracellular PGHs of NCDC 252 were precipitated and characterized. PGHs were screened turbidometrically with Bacillus cereus and Staphylococcus albus as substrates. Spectrum of PGH(s) was studied in renaturing SDS-PAGE by varying substrates and renaturing conditions. PGH(s) band intensity decreased in the presence of NaCl whereas some additional secondary lytic bands appeared in the presence of EDTA. Autolysis of LAB in cheese and other fermented food products is associated with release of oligopeptides by proteolysis and other enzyme activities. Autolytic phenotype of P. acidilactici was evaluated and characterized. Lytic activity studies revealed 45–60% activity against Micrococcus lysodeikticus and B. cereus greater than for P. acidilactici. PGH of P. acidilactici exhibited broad growth inhibiting spectrum of antibacterial activity against studied Gram positive and Gram negative bacteria and thus can be promising in controlling pathogenic bacteria. This also confers probiotic attribute to the studied strain.