Antimicrobial efficacy of lactoferrin, its amidated and pepsin-digested derivatives, and their combinations, on Escherichia coli O157:H7 and Serratia liquefaciens.
OBJECTIVE
To evaluate the in vitro bactericidal efficacy of lactoferrin (LF), its amidated (AMILF) and pepsin-digested (PDLF) derivatives, and their combinations, on Escherichia coli O157:H7 and Serratia liquefaciens.


RESULTS
PDLF exhibited the most potent bactericidal efficacy on E. coli O157:H7 (>2·5 log(10) CFU ml(-1) reduction at concentrations ≥ 1 mg ml(-1)), and AMILF on Ser. liquefaciens (1 log(10) CFU ml(-1) reduction at 0·25-0·50 mg ml(-1)). Some combinations of LF with PDLF or AMILF showed a slight synergy on E. coli O157:H7 and Ser. liquefaciens. However, all combinations of AMILF with PDLF were less active than the sum of the individual effects of the two antimicrobials. Production of capsular polysaccharide by bacteria might be involved in antimicrobial resistance.


CONCLUSIONS
Escherichia coli O157:H7 and Ser. liquefaciens showed marked differences in the sensitivity to LF and its derivatives. E. coli O157:H7 was strongly inhibited by PDLF, whereas the effect of LF and its derivatives on Ser. liquefaciens was weak to negligible.


CONCLUSIONS
PDLF was the most promising of the tested antimicrobials on E. coli O157:H7. However, the resistance of Ser. liquefaciens to LF and its derivatives hinders their use in the food industry.
Departamento de Tecnología de Alimentos, INIA, Madrid, Spain.
A
A
Del Olmo
J
J
Calzada
M
M
Nuñez
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D019453:Escherichia coli O157 / Q000187:drug effects*; D007781:Lactoferrin / Q000378:metabolism / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D010434:Pepsin A / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000187:drug effects; D044090:Serratia liquefaciens / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D011135:Polysaccharides, Bacterial; D007781:Lactoferrin; D010434:Pepsin A