Antibacterial activity of the essential oil of Picea excelsa on Listeria, Staphylococcus aureus and coliform bacteria Original Research Article

Antibacterial activity of essential oil of Picea excelsa was tested with the dilution method against one strain of Listeria ivanovii, six of L. monocytogenes, three of Staphylococcus aureus, three of Escherichia coli, one of Klebsiella oxytoca, one of K. pneumoniae subsp. pneumoniae and one of Enterobacter cloacae. For Gram-positive bacteria in stationary phase, 0·07% of essential oil inhibited about 105colony forming unit per ml; a dose of 0·2–0·3% was bactericidal for 105–107cells contained in 1 ml of liquid culture at 37°C. The coliforms, at a concentration of 105CFU per ml, are resistant whatever the physiological age, since they grow with 8% of essential oil. A simplified technique gives good results for the determination of bactericidal activity against Listeria, only indication against S. aureus.