Since bacteria naturally contain plasmids, when you do a cloning experiment and purify the plasmids at the end, do you get plasmid naturally present in that bacteria in addition to your vector? The standard plasmid purification kits (miniprep, maxiprep, etc.) aren't sequence specific in their purification (they just seem to isolate all plasmids in the cells). I would assume you want a constant purity of vector. Otherwise, for example, you could have 2 vials of plasmid at 1 ug/ uL plasmid while one has 0.4 ug/ mL vector and another 0.8 ug/ mL vector which wouldn't be good for reproducibility. Or is it that the bacteria used for cloning are devoid of naturally present plasmids which would fix this issue?