Antibacterial effect of lactoperoxidase and myeloperoxidase against Bacillus cereus

Abstract

An oral periodontopathic bacterium, Bacillus cereus, was inhibited both by lactoperoxidase (LP) and myeloperoxidase (MP) antimicrobial systems. With the LP-SCN--H202 system, the growth inhibition was directly proportional to the amount of OSCN-ions present. The OSCN-, which is the principal oxidation product of the LP (or MP)-SCN--H202 system at neutral pH, is a normal component of human saliva. The oxidation products of both peroxidase systems inhibited the growth of the bacteria. This inhibition was associated with reduced extracellular release of collagenase activity from the cells. With LP, the antimicrobial efficiency of the oxidizable substrates was SCN-> I-, and with MP, the efficiency was I-> Cl > SCN-, respectively. LP did not oxidize Cl1.

Effects of pH on killing of Staphylococcus aureus and Escherichia coli by constituents of the neutrophil phagolysosome

“…This is compatible with the findings of Riley and Robertson (1984) who reported that activity of a granule-H202 combination against Brucella abortus was greatest at pH 5.5-6, but contrasts with the efficacy of a myeloperoxidase H202-halide system against Bacillus cereus at pH 6-8 (Tenovuo et al, 1985). However, when we compared S. aureus and E. coli at equivalent reagent concentrations in identical incubation conditions, E. coli was killed more rapidly and more completely than S. aureus, especially at pH 7.…”

The lactoperoxidase system links anion transport to host defense in cystic fibrosis

“…Finally, a computational model of LPO activity supported the concept that the effect of the measured decrease in SCN À transport on LPO enzymatic activity could not be compensated by upregulating either LPO or H 2 O 2 and thus predicted a loss of LPO-mediated host defense in CF airways. If the measured difference in apical SCN À between CF and non-CF airway epithelial cells is reflected in vivo, it is likely to be functionally significant since OSCN À production by LPO at the relevant SCN À concentrations are significantly different [33] and bacterial growth in vitro is inversely proportional to the [OSCN À ] [34]. Although certain changes in CF epithelial phenotype in culture have been noted by others, these changes were seen in primary cultures and disappeared after 6-11 days in culture [35].…”

Inactivating effects of the lactoperoxidase system on bacterial lyases involved in oral malodour production

“…The reaction mixture was prepared in an anaerobic environment because the reaction through GO required dissolved oxygen. The reaction mixture in 40 mM phosphate buffer (pH 7.7) was incubated at 37 uC for 10 and 30 min without the addition of bacteria, and the concentration of OSCN -was measured by monitoring the reaction with 5-thio-2-nitrobezoic acid (Tenovuo et al, 1985).…”