Antimicrobial activity of olive mill wastewater extract against Pseudomonas fluorescens isolated from mozzarella cheese

Olive mill wastewater polyphenol extract was tested for antimicrobial activity against 64 strains of Pseudomonas fluorescens responsible for mozzarella discolouration. The extract showed a minimum inhibitory concentration (MIC)₅₀ value of 5 mg/mL and a MIC₉₀ value of 7 mg/mL. The MBC₅₀ and MBC₉₀ values corresponded to 6 and 8 mg/mL, respectively. The MIC concentration (7 mg/mL) was demonstrated to have a bacteriostatic effect while maintaining the bacterial concentration on the levels of the inoculum for 48 hours. The 3/2 MIC concentration was responsible for four logs CFU/mL depletion in colony count after 24 h. As the extract concentration decreased from MIC value, no inhibitory effects were recorded.