Table 2.
Antimicrobial activity (MIC in µg/mL) of cyclic peptides and selected antibiotics against three strains of E. coli for investigation of effects concerning outer membrane permeability. In addition to the laboratory strain E. coli ATCC 25922, the activity against E. coli MC4100 (wild type, WT) and the outer membrane permeable mutant E. coli NR698 was measured and compared.
| E. coli Strains | |||||
|---|---|---|---|---|---|
| ATCC 25922 (from Table 1) |
MC4100 (WT) |
NR698 1 (mutant) |
|||
| Peptide | |||||
| Cyclic peptides | cTurg-1 | >256 | >256 | 64 | |
| W | cTurg-2 | 64 | 16 | 8 | |
| cTurg-3 | 32 | 16 | 8 | ||
| cTurg-4 | 64 | 16 | 8 | ||
| R/W | cTurg-5 | 8 | 8 | 8 | |
| cTurg-6 | 8 | 8 | 8 | ||
| cTurg-7 | 16 | 8 | 8 | ||
| Cyclic lipopeptides | C8-cTurg-1 | 32 | 16 | 8 | |
| C10-cTurg-1 | 8 | 8 | 4 | ||
| C12-cTurg-1 | 4 | 4 | 2 | ||
| W | C8-cTurg-2 | 4 | 8 | 2 | |
| C10-cTurg-2 | 8 | 8 | 4 | ||
| C12-cTurg-2 | 16 | 8 | 8 | ||
| R/W | C8-cTurg-6 | 8 | 8 | 8 | |
| C10-cTurg-6 | 16 | 8 | 8 | ||
| C12-cTurg-6 | 32 | 16 | 16 | ||
| Antibiotics | Polymyxin B | 3.1 | 0.8 | 0.2 | |
| Chlorhexidine | 1.6 | 0.3 | 0.3 | ||
| Vancomycin | 125 | 64 | 0.3 | ||
| Ampicillin | 8 | 8 | 0.3 | ||
| Chloramphenicol | 1.8 | 12.5 | 3.1 | ||
1E. coli MC4100 NR698 imp4213 (with deficient outer membrane).