Bactericidal activity of lactoferrin and its amidated and pepsin-digested derivatives against Pseudomonas fluorescens in ground beef and meat fractions.
The antibacterial activity of lactoferrin (LF) and its amidated and pepsin-digested derivatives (AMILF and PDLF, respectively) against Pseudomonas fluorescens ATCC 948 in ground beef was investigated. LF, AMILF, and PDLF at 1 mg/ml decreased bacterial counts by 1.9, 6.4, and 3.5 log units, respectively, after 1 h at 30 degrees C when the assays were performed in distilled water, but their bactericidal activity disappeared when added at 1 mg/g to ground beef held for 24 h at 5 degrees C. To identify meat components responsible for the loss of bactericidal activity, ground beef was homogenized and separated into fractions of different molecular weights. When cations were removed (fraction > 1 kDa), the bactericidal activity of AMILF was completely restored, whereas the effectiveness of LF and PDLF remained 1.0 and 0.4 log units lower, respectively, than the results obtained in distilled water. EDTA at 5 mM greatly enhanced the bactericidal activity of the three antimicrobials at 1 mg/ml in meat homogenate and in the presence of 5 mM sodium bicarbonate completely restored the bactericidal activity. However, when 1 mg/g AMILF, 5 mM sodium bicarbonate, and increasing EDTA concentrations were added to inoculated ground beef, bacterial counts declined by only 0.2, 0.4, and1.2 log units in the presence of 8, 32, and 128 mM EDTA, respectively, after 24 h at 5 degrees C.
Departamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Carretera de la Coruña Km 7, Madrid 28040, Spain.
Ana
A
del Olmo
Pilar
P
Morales
Manuel
M
Nuñez
D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis / Q000494:pharmacology*; D002417:Cattle; D004492:Edetic Acid / Q000737:chemistry; D005516:Food Microbiology; D007781:Lactoferrin / Q000032:analysis / Q000494:pharmacology*; D008460:Meat / Q000382:microbiology*; D010434:Pepsin A / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D004492:Edetic Acid; D007781:Lactoferrin; D010434:Pepsin A