title: Optimization of the components concentrations of the lactoperoxidase system by RSM.
abstract: OBJECTIVE
  The aim of this work was to use response surface methodology (RSM) approach, a statistical mathematical tool, to model effects and interactions of glucose oxidase (GOD), glucose, lactoperoxidase (LPO) and pH-values on the thiocyanate (SCN-) peroxidation, to determine the best concentrations of lactoperoxidase system (LP-s) components in order to obtain maximal SCN- peroxidation and so to enhance the LP-s antibacterial effects.
  
  
  RESULTS
  Experimental design using RSM was used for modelling effects and interactions of GOD (28.5-142.5 IU l(-1)), glucose (0.55-11.11 mmol l(-1)), LPO (0-6284 IU l(-1)) concentrations, and pH-values (6.0-7.4) on thiocyanate peroxidation. A fixed SCN- concentration of 0.5 mmol l(-1) was used. Experiments were carried out at 4 or at 25 degrees C in 0.1 mol l(-1) phosphate buffer. Optimized concentrations for both temperatures (4 and 25 degrees C) were quite similar and were 85.5 IU l(-1) for GOD, 8 mmol l(-1) for glucose and 3927.5 IU l(-1) for LPO at an initial pH-value of 6.5. SCN- peroxidation was more efficient at 25 than at 4 degrees C. At 4 degrees C, no interaction between factors occurred. At 25 degrees C, thiocyanate peroxidation was affected by GOD/glucose, GOD/pH and LPO/pH. Thiocyanate peroxidation was mainly increased by glucose and LPO factors. The optimized system had a bacteriostatic effect on Listeria monocytogenes CIP 82110(T) and a strong bactericidal effect on Pseudomonas fluorescens CIP 6913(T).
  
  
  CONCLUSIONS
  Appropriate combinations of LPO, GOD, glucose concentrations and pH-values allowed maximal thiocyanate peroxidation and enhanced the antibacterial effect of the LP-s.
  
  
  CONCLUSIONS
  This optimization by RSM approach allowed a better understanding of the LP-s functioning, the description of the component impacts on the SCN- peroxidation, and the observation of different interactions between the factors. The antimicrobial efficiency of LP-s can be enhanced by better concentration ratios of the LP-s components.
authors.affiliation: Laboratoire de Sciences et Génie Alimentaires, Ecole Nationale Supérieure d'Agronomie et des Industries Alimentaires-Institut National Polytechnique de Lorraine (ENSAIA-INPL), Vandoeuvre-lès-Nancy cedex, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Adolphe
authors.forename: M
authors.initials: M
authors.lastname: Jacquot
authors.forename: M
authors.initials: M
authors.lastname: Linder
authors.forename: A-M
authors.initials: AM
authors.lastname: Revol-Junelles
authors.forename: J-B
authors.initials: JB
authors.lastname: Millière
mesh_terms: D003627:Data Interpretation, Statistical; D005947:Glucose / Q000737:chemistry; D005949:Glucose Oxidase / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007784:Lactoperoxidase / Q000737:chemistry*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D013696:Temperature; D013861:Thiocyanates / Q000737:chemistry
chemical_list: D013861:Thiocyanates; D005949:Glucose Oxidase; D007784:Lactoperoxidase; D005947:Glucose; C031760:thiocyanate