Antibacterial activities of secondary metabolites from Clitocybe nuda

Abstract

The purpose of this study was to obtain a better understanding of the antibacterial activities of the secondary metabolites from Clitocybe nuda, one kind of edible mushroom. The antibacterial activity was determined by testing the Minimum Inhibitory Concentrations (MIC) of 50% log reduction of the secondary metabolites from C. nuda against four prevalent foodborne pathogens---Listeria monocytogenes, Salmonella Typhimurium, Staphylococcus aureus and Escherichia coli O157:H7, which were 27, 25, 23 and 40 mg/mL respectively. The thermal and pH-stability of the antibacterial activity of the secondary metabolites from C. nuda were also evaluated. They were stable at 121 °C after 30 min treatment and had good antibacterial activity under a broad pH range of 5-9. The antibacterial efficacies in liquid eggs and ground beef were also investigated. The secondary metabolites of C. nuda were able to reduce about 0.2 and 0.5 log CFU/g L. monocytogenes and E. coli O157:H7 in ground beef, respectively. A 1 log reduction of Salmonella Typhimurium in liquid eggs at 50 mg/mL treatment was found.