TABLE 1.
Bacterial strains used as references in this study.
| Organism | Source and reference |
| Citrobacter freundii | CECT 7464 |
| Citrobacter youngae | CECT 5335 |
| Enterobacter aerogenes | CECT 648 |
| Escherichia coli | |
| K-12 (MG1655) | This laboratory (Molina et al., 1998), ATCC 700926 |
| MG1655 λ+ | This laboratory |
| B (Luria) | CECT 4201 |
| B/r | CECT 105 |
| Bi | CECT 4537 |
| BW6164 | CGSC 6759 |
| C (Sinsheimer) | ATCC 13706 |
| W1 (Waskman) | CECT 99 |
| W2 (Stoke) | CECT 727 |
| C600 | Gift from Dr. Rouviere-Yaniv, ATCC 23724 |
| GY752 | This laboratory (Sommer et al., 1998) |
| VIP45 λ+ | Gift from Dr. Miguel Vicente |
| Hafnia alvei | CECT 158 |
| Klebsiella pneumoniae | CECT 143 |
| Lactobacillus acidophilus | CECT 903 |
| Lactobacillus casei | CECT 475 |
| Lactococcus lactis ssp. Lactis | CECT 185 |
| Salmonella typhimurium | CECT 722 |
| Serratia marcescens | CECT 846 |
| Shigella boydii | CECT 583 |
| Shigella flexneri 2a | CECT 585 |
| Shigella flexneri 2b | CECT 4804 |
| Shigella sonnei | CECT 4887 |
| Yersinia enterocolitica | CECT 4315 |
ATCC, American Type Culture Collection (United States); CECT, Colección Española de Cultivos Tipo (Spain); CGSC, Coli Genetic Stock Center (United States).