In vitro antimicrobial and antibiofilm-forming activities of Origanum munzurense plant extract on some foodborne gram-negative bacteria

Plants are an important source for the discovery of antimicrobial formulations due to the many biologically active components they contain. In this study, in vitro antimicrobial and antibiofilm forming activities of ethanolic extract of Origanum munzurense were investigated against some strains of foodborne pathogenic bacteria. To investigate the antimicrobial activity, the minimal inhibitory concentration values against the selected bacteria and antibiofilm-forming activity were tested with the liquid microdilution method and microplate method, respectively. MICs of Origanum munzurense extract against the bacteria tested are 32 mg/mL for Escherichia coli O157: H7 ATCC 35150, 32 mg/mL for Escherichia coli O157: H7 ATCC 43895, 16 mg/mL for Salmonella enteritidis ATCC 13076, 16 mg/mL for Salmonella typhimurium ATCC 700408, 32 mg/mL for S. typhimurium ATCC 14028, and 2 mg/mL for Pseudomonas fluorescens ATCC 13525. Origanum munzurense showed the best antibacterial effect on Pseudomonas fluorescens ATCC 13525 strain. The least antibacterial effect was shown on E. coli O157:H7 ATCC 35150, E. coli O157:H7 ATCC 43895, and Salmonella typhimurium ATCC 14028. Origanum munzurense extract inhibited biofilm formation on Salmonella enteritidis ATCC 13076 strain at a concentration of 16 mg/mL. Antibiofilm formation was not observed for other bacteria. Total phenolic content of Origanum munzurense was 539 mg of gallic acid equivalent (GAE)/L. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity O.of munzurense extract was determined to be 18 & mu;g/L. In conclusion, Origanum munzurense ethanol extract has a range of antibacterial effects on the selected foodborne pathogenic bacteria and showed antibiofilm-forming activity especially for S. enteritidis ATCC 13076. In addition, the plant has the prominent amount of phenolic content with antioxidant and radical scavenging activity.