BIOTECHNOLOGICAL APPROACHES FOR TARGETING SPORE-FORMING BACTERIA AND FOODBORNE PATHOGENS
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The growing demand for organic products and the rising antibiotic resistance of some bacteria underscore the need for biotechnological approaches to control spoilage and pathogenic species.The lactoperoxidase system (LPS) is a natural antimicrobial system in milk, activated by H₂O₂, which is produced during lactose oxidation to lactobionic acid by lactose oxidase (LOx). H₂O₂ can also serve as an antimicrobial agent when applied at appropriate concentrations. The use of LOx can generate H₂O₂ while enhancing LPS efficacy, providing a strategy to extend dairy product shelf life. A first study evaluated LOx’s antimicrobial effects mediated by H₂O₂ production against 28 spore-forming strains from dairy facilities using an overlay assay to determine effective concentrations. Results showed that 15 strains were inhibited at 1.7 mg/L LOx, 10 additional strains at 17 mg/L, and the remaining 3 strains (Bacillus subtilis, B. paralicheniformis, B. gibsonii) only at 170 mg/L LOx. LOx proved effective as growth inhibitor and could be added to dairy products in early production stages. A second study assessed the effectiveness of hydrogen peroxide (HP), phosphoric acid (PA), and a commercial sanitizer (CS) as chlorine alternatives for reducing dairy spore formers on PVC, stainless steel, and rubber surfaces. Using AOAC Method 2008.05, results indicated that HP was the only effective sanitizer, achieving ≥4 log reductions on PVC and stainless steel, and ≥3 log reductions on rubber. Neither PA nor CS achieved more than a 1 log-unit reduction. However, high concentrations of HP or acid raised concerns regarding corrosion, target ambiguity, and potential sensory/nutritional changes. To address these limitations, a third study synthesized antibody-oxidase conjugates and compared their inhibition potential against target pathogens to that of unconjugated sugar oxidases. Glucose and lactose oxidases were conjugated to an antibody specific for Listeria monocytogenes and tested against 2 log CFU/ml cultures. Results showed greater inhibition when both antibody and enzyme were present, allowing a 50% reduction in the required glucose oxidase concentration. In conclusion, antibody-sugar oxidase conjugates represent promising food-safety tools capable of targeting specific pathogens while minimizing secondary effects. These natural biocontrol strategies offer novel solutions against spore-forming bacteria and foodborne pathogens in dairy environments.