Antimicrobial efficacy of lactoferrin, its amidated and pepsin-digested derivatives, and their combinations, on Escherichia coli O157H7 and Serratia liquefaciens
Olmo, Ana del | Calzada Gómez, Javier | Núñez Gutiérrez, Manuel
Aims To evaluate the in vitro bactericidal efficacy of lactoferrin (LF), its amidated (AMILF) and pepsin-digested (PDLF) derivatives, and their combinations, on Escherichia coli O157H7 and Serratia liquefaciens.Methods and Results PDLF exhibited the most potent bactericidal efficacy on E. coli O157H7 (>2.5 log10 CFU ml-1 reduction at concentrations ≥1 mg ml-1), and AMILF on Ser. liquefaciens (1 log10 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 O157H7 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 O157H7 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.Significance and Impact of the Study: 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. © 2010 The Authors. Letters in Applied Microbiology © 2010 The Society for Applied Microbiology.
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