Several pBR DNA plasmid storage conditions were evaluated in this study, including the storage form (liquid
or dried on 3M paper), the buffer used to dissolve the plasmid, and temperature. Storage in the liquid form resulted in increased
colony formation compared to DNA dried on paper, which is a more convenient and often preferred method for
shipping plasmids. The TE buffer was superior to autoclaved H2O for DNA storage. The most important factor for longterm
storage was temperature, and storage at -20°C in TE buffer showed good results (ca. 107 cfu/mg plasmid DNA) for
up to 270 days. In contrast, stored DNA plasmid in H2O or dried on What man 3M paper at 20°C, preferred for ordinary
DNA shipment, resulted in deteriorated yields after 90 days. In conclusion, my results indicate that 20°C is acceptable for
short-term storage (up to 18days), but TE buffer and -20°C should be used for longer-term storage.