A Study on Biofilms Inhibition and Preservative Activity of Pomegranate Peel Methanol Extract (PPME)

Objectives: Microorganisms with biofilms are associated with chronic human infections (highly resistant to antimicrobial agents). Pomegranate is used in treatment of several diseases, as its peels contain phenolic compounds and hydrolysable tannins. We aimed to study the effect of PPME on inhibition of biofilms and as a natural preservative in food industrial application. Methods: Pomegranate peel was extracted with methanol. E. coli clinical isolates were identified by standard microbiological procedures. Antibiotic susceptibility testing was performed using disc diffusion method. Antibacterial activity of PPME was tested using agar well diffusion assay. Minimum Inhibitory Concentration (MIC) was evaluated according to The European Committee on Antimicrobial Susceptibility Testing (EUCAST) agar dilution method. Biofilms detection was done by Tube method. Total phenolic content (TPC) in PPME was determined using spectrophotometric method. PPME ability to scavenge (1, 1diphenyl-2-picryl hydrazyl) DPPH free radicals was assessed by the standard method. Total antioxidant capacity of PPME was evaluated by phosphormolybdenum method. Total Phenolic Content (TPC) for cooked patties was freshly analyzed at different concentrations (1-0.25mg/ml). Results: Tested isolates were multidrug resistant. High antibacterial activity of PPME was found. MIC of PPME was found to be 10mg/ml. Tested isolates were biofilms producers, PPME largely affected on biofilm forming ability. TPC for treated group was (2785.19-349.22 µg/kg): for untreated group was 1251-226 µg/kg). DPPH radical scavenging activity was 38.12-5.45%. Thiobarbituric Acid Reactive Substances (TBARS) values were measured for samples from (0 -9 days) of storage period which was 0.522-1.3,0.859-1.816mg malonladehyde/kg meat for treated, untreated group respectively. AOA% was 31.49-66.92 from (0 – 9) days of storage. Conclusions: PPME was able to inhibit biofilm formation in tested isolates and can be promising in inhibiting contamination caused by biofilm forming bacteria in food industry.