1048 A DNA prism for high - speed continuous fractionation of large DNA molecules

10 volumes of Luria–Bertani (LB) medium containing Tet and Kn and grown to saturation. To begin the third positive selection, a 25 ml GMML culture containing Tet, Kn, and 1 mM pIF, pAF, pCF, or OAY was inoculated with cells from the negative screen (100 μl, pelleted and resuspended in GMML). After incubation for 3 h at 37°C, Cm was added to a final concentration of 75 μg/ml, and cells were grown to saturation (∼24 h). Following the third positive selection, cells were plated on GMML–agar containing Tet, Kn, 0.002% Ara, 0, 75, or 100 μg/ml Cm, and 0 or 1 mM pIF, pAF, pCF, or OAY, and grown for 48 h at 37°C.