TABLE 4.
Effects of different recA or lexA mutations on RS1-mediated excision of CTX prophage from toxigenic V. cholerae strains
| Straina | Frequency of loss of CTX prophage upon treatment of parent strain |
|
|---|---|---|
| Infection with RS1-Cmϕ | Transformation with pRstC | |
| G-7555 | 2.3 × 10−2 | 6.1 × 10−2 |
| G-7555 recA::TnFGL3 | <1 × 10−7b | <1 × 10−7b |
| G-7555 lexA::TnFGL3 | 1.7 × 10−2 | 2.3 × 10−2 |
| G-3985 | 9.1 × 10−3 | 4.2 × 10−2 |
| G-3985 recA::TnFGL3 | <1 × 10−7b | <1 × 10−7b |
| G-3985 lexA::TnFGL3 | 2.4 × 10−2 | 1.3 × 10−2 |
| AL33457 | 6.8 × 10−3 | 8.3 × 10−3 |
| AL33457 recA::TnFGL3 | <1 × 10−7b | <1 × 10−7b |
| AL33457 lexA::TnFGL3 | 5.2 × 10−3 | 2.2 × 10−2 |
a
Extensive subculture of all wild-type toxigenic strains in vitro or passage in rabbits without infection with RS1-Kmϕ or transformation with pRstC did not produce any detectable CTX-negative derivatives.
b
No CTX-negative colonies were found among 107 Kmr recipient cells screened.