Dry-heating of lysozyme increases its activity against Escherichia coli membranes.
For food as well as for medical applications, there is a growing interest in novel and natural antimicrobial molecules. Lysozyme is a promising candidate for the development of such molecules. This protein is largely studied and known for its muramidase activity against Gram-positive bacteria, but it also shows antimicrobial activity against Gram-negative bacteria, especially when previously modified. In this study, the activity of dry-heated lysozyme (DH-L) against Escherichia coli has been investigated and compared to that of native lysozyme (N-L). Whereas N-L only delays bacterial growth, DH-L causes an early-stage population decrease. The accompanying membrane permeabilization suggests that DH-L induces either larger pores or more pores in the outer membrane as compared to N-L, as well as more ion channels in the inner membrane. The strong morphological modifications observed by optical microscopy and atomic force microscopy when E. coli cells are treated with DH-L are consistent with the suggested disturbances of membrane integrity. The higher hydrophobicity, surface activity, and positive charge induced by dry-heating could be responsible for the increased activity of DH-L on the E. coli membranes.
Agrocampus Ouest, UMR1253 Science et technologie du lait et de l'œuf , F-35042 Rennes, France.
Melanie
M
Derde
Catherine
C
Guérin-Dubiard
Valérie
V
Lechevalier
Marie-Françoise
MF
Cochet
Sophie
S
Jan
Florence
F
Baron
Michel
M
Gautier
Véronique
V
Vié
Françoise
F
Nau
D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D009113:Muramidase / Q000737:chemistry* / Q000494:pharmacology*; D055550:Protein Stability
D000900:Anti-Bacterial Agents; D009113:Muramidase