Antimicrobial activity of a 14-residue peptide against Escherichia coli O157:H7.
An amphiphilic, cationic peptide composed of eight leucines and six lysines was synthesized by solid phase peptide synthesis (SPPS). The synthetic peptide was bactericidal within 10 min at concentrations as low as 3 microg ml - 1 against mid-exponential Escherichia coli O157:H7 suspended in buffer. Concentrations of 25 microg ml - 1 caused up to 7 log10 cfu ml - 1 reductions. When tested against E. coli O157:H7 grown in TSB, the peptide was bactericidal and bacteriostatic at concentrations of 50 and 25 microg ml - 1, respectively. An inhibitory effect was also observed against stationary phase cells. The synthetic peptide caused the release of u.v.-absorbing materials from the E. coli O157:H7 as well as an increase in its O.D.600 nm. Intracellular K+ and ATP depletion were also observed. These results suggest that the peptide increased the cell membrane permeability but it did not lyse the cells.
Appendini
P
P
Institute of Food Science, Cornell University, Ithaca, NY 14853, USA.
Hotchkiss
J H
JH
D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D007930:Leucine / Q000737:chemistry; D008239:Lysine / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D010455:Peptides; D007930:Leucine; D008239:Lysine