In vitro Antibacterial Activity of the Lactoperoxidase System Towards Enterotoxigenic Strains of Escherichia coli

Abstract

The lactoperoxidase-thiocyanate-hydrogen peroxide (LP) system inhibited the growth of enterotoxigenic Eschrrzchia coli strains responsible for scouring in neonatal and post-weaning piglets. An enzymatic system for hydrogen peroxide generation (glucose oxidase, GO; 0.1 U/ml) and a chemical source (sodium carbonate peroxyhydrate, SCP; 90 mg/l) were used in the LP system to test 19 strains in a 6-h growth assay at 37°C. Only three strains were highly sensitive to the LP/GO system, while all exhibited significant growth inhibition with the LP/SCP system. Hydrogen peroxide alone had less effect than the complete system. The bactericidal activity of the LP/GO system towards a previously resistant strain was greatly increased by increasing the level of glucose oxidase in the system by three-or five-fold. US. Copyright ClearanceCenter Code Statement: 0931 -1793/92/39O7-0537$02.50/0 538 GRIEVE, DIONYSIUS and Vos examined the in d u o antibacterial activity of the LP system towards enterotoxigenic strains of porcine E. Cali isolated from cases of neonatal and post-weaning scours. The effects of two exogenous sources of hydrogen peroxide, a glucose/glucose oxidase H202generating system and a chemical system (sodium carbonate peroxyhydrate, SCP) on the antibacterial activity of the LP system were also studied. Material and Methods Bacteria and Culture ConditionsEnterotoxigenic Escherichia coli (ETEC) strains were isolated from cases of neonatal and postweaning scours in piglets. Eight isolates (PEC 1-8) were obtained from the Regional Veterinary Laboratory (Wagga Wagga, NSW, Australia) and were kindly provided by Dr. PAT BLACKALL (Animal Research Institute, Brisbane, Q., Australia). Eleven isolates were kindly provided by Dr. TONY FAHY (Regional Veterinary Laboratory, Bendigo, Vic., Australia).Each isolate, on receival at the laboratory, was allocated a laboratory reference number (PEC 1 -19), regenerated in Isosensitest broth (Oxoid Limited, Basingstoke, Hampshire, England), and inoculated and grown overnight on peptone-yeast extract (PYE) agar slants at 37°C. PYE agar

Extending the Technological Validity of Raw Buffalo Milk at Room Temperature by Esterified Legume Proteins

“…Hydrogen peroxide is also unstable and may react with milk proteins. In addition, most gramnegative bacteria possess catalase enzyme that decomposes hydrogen peroxide and thus cannot effectively be inhibited by this system (Grieve et al 1992). Some mutants of Escherichia coli with tolerance to LP-s have been isolated (De Spiegeleer et al 2005).…”

Antimicrobial actions of dual oxidases and lactoperoxidase

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