Antibacterial Activity of the Lactoperoxidase System Against Salmonella typhimurium in Trypticase Soy Broth in the Presence and Absence of a Heat Treatment

Abstract

The antibacterial activity of the lactoperoxidase system (LP system) on the growth and survival of Salmonella typhimurium in tryptic soy broth (TSB) was determined. The LP system, consisting of lactoperoxidase (1 μg/ml), potassium thiocynante (KSCN) (5.9 mM) and H2O2 (2.5 mM), was found to have both bacteriostatic and bactericidal activities against strains of S. typhimurium. The bactericidal activity was clearly dependent on the initial inoculum level. Levels of 102 - 105 CFU/ml were killed at 37°C as opposed to the bacteriostatic activity with inoculum levels of 106 - 107 CFU/ml, which exhibited a 25-h lag. The LP system also enhanced thermal inactivation of S. typhimurium. D50°C-values were > 60 min (untreated broth) and 12 min (LP system activated); corresponding D52°c-values were 20 min and 7.5 min; corresponding D55°c-values were 14 min and 4 min; corresponding D60°C -values were 5 min and 2.5 min and corresponding Devalues were .31 min and .20 min.

Susceptibility of Helicobacter pylori and its urease activity to the peroxidase-hydrogen peroxide-thiocyanate antimicrobial system

“…The short-lived bactericidal effect of the system on H. pylori is in agreement with previous reports of studies with other species of bacteria, in which H 2 O 2 was introduced only at the initiation of the reaction [34,35]. SCN À was used at a concentration of 0.66 mM throughout this study.…”

Antimicrobial Effects of Lactoferrin, Lysozyme, and the Lactoperoxidase System and Edible Whey Protein Films Incorporating the Lactoperoxidase System Against Salmonella enterica and Escherichia coli O157:H7

“…The structural damage of microbial cytoplasmic membranes by the oxidation of SH-groups results in eventual death of the cells (Reiter and Harnulv 1984;Kussendrager and van Hooijdonk 2000). Antimicrobial activities of LPOS against Salmonella and E. coli O157:H7 have been reported (Wolfson and Sumner 1994;Kennedy and others 2000;Elliot and others 2004).…”

“…Those LPOS treatments had bactericidal effects against S. enterica and E. coli O157:H7 in TSB. Wolfson and Sumner (1994) reported LPOS, consisting of LPO at 1 ppm, was bactericidal to 10 3 to 10 5 CFU/mL of S. typhimurium in TSB at 37 °C. WPI films incorporating LPOS, which exhibited effective antimicrobial activity against S. enterica and E. coli O157:H7 in the turbidity test, were evaluated for their ability to inhibit the 2 pathogens using a disc-covering test and a disc-surface-spreading test.…”

“…LF inhibits microorganisms by binding iron and making this essential component unavailable to microorganisms (Tomita and others 2002;Walzem and others 2002). Several researchers reported antibacterial activity of LF against Salmonella and E. coli (Naidu and others 1993;Yamauchi and others 1993;Wolfson and Sumner 1994;Shin and others 1998). LZ hydrolyses ␤-1,4 linkages between Nacetylmuramic acid and 2-acetyl-amino-2-deoxy-D-glucose residues in peptidoglycan of bacterial cell wall, resulting in lysis of microbial cells (Shah 2000).…”

Role of Porins in Sensitivity of Escherichia coli to Antibacterial Activity of the Lactoperoxidase Enzyme System

“…When LP is applied at physiological concentrations, the effect of the LP system is mainly bacteriostatic, which may be related to the fact that thiol-disulfide conversions are reversible. At higher concentrations or when cells are appropriately sensitized, for example, by heat (48) or hydrostatic pressure treatment (10), the LP system can have a bactericidal effect. This bactericidal effect may be related to the production of small amounts of oxygen radicals by the LP system (4), which cause irreversible protein oxidation by the formation of carbonyl groups.…”