Summary and Implications
This study evaluated the effect of EDTA and lysozyme on the antibacterial activities of activated ovotransferrin against 5 strains of L. monocytogenes. First, a disc test was performed to screen the concentrations of EDTA or lysozyme that showed antibacterial activities in ovotransferrin (O) or ovotransferrin in 100 mM NaHCO3 (OS) solution. Turbidity and viability test were conducted using O or OS solution combined with either lysozyme (OL and OSL) or EDTA (OE and OSE). Also, OS combined with 2 mg/ml lysozyme (OSL) or/and 1 mg/ml EDTA (OSLE) were applied on commercial hams to determine if the solutions show antibacterial activities on meat products. The effect of initial cell population on the antibacterial activities of ovotransferrin combined with either EDTA or lysozyme was also determined. L. monocytogenes started to grow after 1 day of incubation in the presence of > 2.0 mg/ml lysozyme. OL groups showed weak antibacterial activities against L. monocytogenes in BHI broth culture and their activities were bacteriostatic. OSL groups were bactericidal against L. monocytogenes, resulting in 1 log reduction from initial cell population. Even though OSL showed stronger antibacterial activity than OS, lysozyme had no significant effect on antibacterial activity of OS against L. monocytogenes. Also, EDTA itself at 1.0 and 2.0 mg/ml were bacteriostatic against 5 strains of L. monocytogenes. They were more susceptible to EDTA than lysozyme, and OSE1 and OSE2 had bactericidal activity against L. monocytogenes. There was a significant difference in the survivor cell populations between OS and OSE groups (p < 0.05). Therefore, EDTA enhanced the antibacterial activity of OS against L. monocytogenes. However, ovotransferrin plus either lysozyme or/and EDTA did not show any antibacterial effect in commercial hams during storage at 10 o C. In addition, the initial population of L. monocytogenes cells influenced the antibacterial activity of OSL or OSE.
Iowa State University
Ko, Kyung Yuk; Mendonca, Aubrey F.; and Ahn, Dong U.
"Effect of EDTA and Lysozyme on the Antimicrobial Activity of
Ovotransferrin against Listeria monocytogenes,"
Animal Industry Report:
AS 656, ASL R2495.
Available at: http://lib.dr.iastate.edu/ans_air/vol656/iss1/16