Antimicrobial activity of some potential active compounds against food spoilage microorganisms
Antimicrobial activities of six potential active compounds (acetic acid, chitosan, catechin, gallic acid, lysozyme, and nisin) at the concentration of 500 g/ml against the growth of Escherichia coli, Staphylococcus aureus, Listeria innocua, and Saccharomyces cerevisiae were determined. Lysozyme showed the highest antimicrobial activity against L. innocua and S. cerevisiae with an inhibition zone of 19.75 and 17.37 mm, respectively. Catechin was strongly active against E. coli, L. innocua, and S. aureus with 15.37, 19.38, and 17.00 mm of inhibition zone diameter, respectively. The minimum inhibitory concentration (MIC) value of catechin for E. coli and for S. aureus was the same at 640 μg/ml, while the minimum bactericidal concentration (MBC) values were 640 and 1,280 μg/ml, respectively. The MIC and MBC values of lysozyme for L. innocua were 160 and 640 μg/ml, respectively. S. cerevisiae was the most susceptible microorganism to lysozyme among others, since both its MIC and MBC were the lowest (2.5 μg/ml). However, catechin and lysozyme were combined in equal amounts; all tested microorganisms were effectively inhibited as indicated by both qualitative and quantitative antimicrobial activities. This study thus revealed the potential application of some active compounds such as catechin and lysozyme for their usage in food products.
Keywords: Antimicrobial activity, catechin, lysozyme, agar disc diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC)