Antibacterial activities of Clitocybe nuda extract on foodborne pathogens

Abstract

The addition of antimicrobial agents to foods is an important approach for controlling foodborne pathogens to improve food safety. Currently, most antimicrobial agents in foods are synthetic compounds. Researchers are looking for natural antimicrobial agents to substitute for synthetic compounds in foods to control microbial growth in foods. Clitocybe nuda is an edible macrofungus which produces a large number of biologically active compounds with antibacterial activities. The purpose of this study was to evaluate the antibacterial activities of Clitocybe nuda extract on foodborne pathogens and its stability at different temperatures and pHs, and to estimate the molecular weights of some of the antibacterial components of the fungus. The antimicrobial activity was evaluated by testing the minimum inhibitory concentration (MIC) on four foodborne pathogens: Listeria monocytogenes, Salmonella typhimurium, E. coli O157:H7, and Staphylococcus aureus. The stability of the extract was tested at pH 4-10, and temperatures of 4, 72, 100, and 121°C. The growth of pathogens was significantly inhibited by the Clitocybe nuda extract. The MIC50 for Listeria monocytogenes, Salmonella typhimurium, E. coli O157:H7 and Staphylococcus aureus are 79.20, 84.51, 105.86, and 143.60 mg/mL, respectively. The antibacterial activities among heat-treated Clitocybe nuda extracts were not affected by heat, and there was no significant different among the four temperatures evaluated (p≥0.05). The pH had no negative impact on the antibacterial activities. The data indicate that the extract can effectively control the growth of foodborne pathogens and is very stable at high temperatures and over a wide range of pH.