Bacterial lysis phenotype of pLYS.

<p>(A) <i>S. typhimurium</i> carrying pLYS were grown in LB supplemented with L-arabinose. When the optical density (A₆₀₀) of the culture reached ∼1.0, at T = 2 hrs, the LB was supplemented with L-arabinose in half of the cultures. The A₆₀₀ of the culture was measured at regular time intervals (circles) and viable bacteria were determined by CFU counting (bars). Open circles and bars represent bacteria samples without L-arabinose addition, and filled circles and bars represent bacterial samples with L-arabinose addition. (B) <i>S. typhimurium</i> carrying either pLYS<i>P_BAD::lacZ</i> or pBAD24<i>P_BAD::lacZ</i> grown in LB was supplemented with L-arabinose when the A₆₀₀ of the culture reached ∼1.0. The bacterial culture was taken 2 hrs after the addition of L-arabinose, separated into bacterial pellet and supernatant by centrifugation and filtration, and assayed for total β-galactosidase activity. Data represent mean ± S.D., and asterisks (*) indicate a significant difference compared between supernatant of pLYS<i>P_BAD::lacZ</i> and pBAD24<i>P_BAD::lacZ</i> (***, P<0.0001). (C) The same samples were analyzed for β-galactosidase expression by Western blot analysis. 50 µg of sonicated samples were analyzed. Bacterial whole culture not induced for bacterial lysis was included.