BACTERIAL-GROWTH MEDIUM THAT SIGNIFICANTLY INCREASES THE YIELD OF RECOMBINANT PLASMID

Isolation of plasmid DNA from Eschericia coli is a daily activity in m any molecular biology laboratories. A number of protocols and media re cipes have been reported in an effort to make this process more effici ent Here we describe a growth medium that supports much higher E. coli cell densities and, concomitantly, a much higher yield of plasmid tha n previously reported for small-scale applications. On a unit volume b asis, E. coli cultures grown in this medium, termed H15, produce up to 30-fold more recombinant plasmid than in conventional rich media, par alleling the increase in cell density. This phenomenon is independent of E. coli host strain, DNA insert size and plasmid copy number H15 me dium is also very economical; as much as 6 mg of plasmid cart be harve sted per dollar of medium.