Lysates!

Well, lysates aren't really that exciting, but it's been a while since I got to do anything with phage. I used both the turbid-plaque and the clear-plaque streaks to infect two cultures, one with the ppdD::lacZ reporter fusion and one with the sxy::kan knockout. They all grew up nicely and then promptly lysed. Titering showed that the clear-plaque phage gave about 2x10^10 pfu/ml, all the small clear plaques expected of P1vir. The other phage gave a mix of clear and turbid plaques, suggesting that the colleague who made the source lysate had neglected to start from a single plaque (naming no names).

Today I'm going to make a good stock lysate, by infecting the "wild type" E. coli strain W3110. (I put wild type in quotes because the strain does not carry the lambda phage present in the original "wild" K-12 isolate. And I'm going to do the transduction that was the point of getting a P1 lysate, to create a strain carrying both the ppdD::lacZ reporter and the sxy::kan knockout). I have lysates of both strains so I'll try the transduction in both directions, each selecting for AmpR KanR (the reporter carries AmpR). And a control transduction transferring lacY from W3110 into C600.