Optimization of bacterial culture and plasmid purification
Sandrine Hamels, Blandine Vanbellinghan, Eppendorf Application Technologies S.A.
Rafal Grzeskowiak, Eppendorf AG
Plasmid purification from bacterial culture is a commonly performed protocol in molecular biology and life science laboratories. For medium scale preparations, 15 mL conical tubes with screw caps are typically used which often pose handling drawbacks and don't enable achieving optimal productivity of bacterial culture and maximal yields of DNA.
In this Application Note, we show that the bacterial culture productivity and DNA yields using 25 mL tubes were much higher when compared to standard 15 mL conical tubes and at the same time provided improved handling and performance of the workflow.
Bacterial culture and subsequent plasmid purification are undoubtfully one of the most commonly performed protocols in molecular biology and life science laboratories. Despite increasing availability and affordability of plasmid purification kits from numerous providers, the standard method of alkaline lysis  is still widely used and remains mainstream in the academic sector. It is cost effective, scalable and typically produces high yields of pure plasmid DNA, which can be directly used in various down-stream applications like DNA digestion, cloning, or sequencing.