In Vitro Antimicrobial Activity of the Alcoholic Extract of Quercus brantii subsp. persica

Lately, consumption of natural preservatives to improve food products' shelf life has been the center of attention. Due to the approved health benefits of the oak fruit, its application in food industry as a preservative seems satisfying.

Antimicrobial activity of the alcoholic extract of the oak fruit in concentrations of 200, 400, 600 and 800 mg/mL was investigated on Escherichia coli, Staphylococcus aureus, Salmonella typhi, Klebsiella pneumoniae, and Saccharomyces cerevisiae with well diffusion technique. In order to detect the minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC), macro-dilution broth and subculturing on solid culture media techniques were used.

The most growth prevention and inhibitory effect was observed in S. aureus, S. cerevisiae, K. pneumoniae, S. typhi, and E. coli, respectively. The most and the least antimicrobial activity of the oak fruit extract were observed in S. aureus (MIC=0.15 mg/mL and MBC = 0.313 mg/mL) and E. coli (MIC = 2.5 mg/mL and MBC=5 mg/mL), respectively.

The alcoholic extract of Iranian oak fruit had antimicrobial activity, and its impact was more profound on gram-positive bacteria such as S. aureus and S. cerevisiae than gram- negative ones namely E. coli, K. pneumoniae, and S. typhi.