Antibacterial activity of water-soluble extract from pine needles of Cedrus deodara

The antibacterial activity of water-soluble extract from pine needles of Cedrus deodara (WEC) was evaluated on five food-borne bacteria, and its related mechanism was investigated by transmission electron microscope. In vitro antibacterial assay showed that WEC possesses a remarkable antibacterial activity against tested food-borne bacteria including Escherichia coli, Proteus vulgaris, Staphylococcus aureus, Bacillus subtilis and Bacillus cereus, with the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values in the ranges of 0.78–12.5 mg/ml and 1.56–25 mg/ml, respectively. In a food system of fresh-squeezed tomato juice, WEC was observed to possess an effective capacity to control the total counts of viable bacteria. Shikimic acid was isolated from WEC and identified as the main antibacterial compound. All results of our study suggested that WEC might be a new potential source of natural antibacterial agents applicable to food.