Possible Degradation of Plasmid in Escherichia coli DH5α Stored at 4 oC

Abstract

Large amount of plasmids are typically produced in Escherichia coli DH5α through cell-based replication mechanisms. Typically, such cells are harvested, and the plasmid extracted for downstream molecular biology workflow after going through a plasmid extraction step. This work explores the feasibility of storing the plasmid in cells which is stored at 4 oC for two weeks. Results revealed that compared to the initial plasmid concentration extracted from newly harvested cells, considerable plasmid concentration remain extractable from the cells after 4 days of storage. But, no plasmid could be extracted from the cells after 15 days of cell storage at 4 oC. Overall, the result suggests that it is not feasible to store cells with plasmid at 4 oC for long-term without incurring plasmid degradation and complete loss of the plasmid after 2 weeks. Possible reasons could be degradation of the plasmid to supply nucleotides, which through metabolic pathways, supply carbon for the cells subsisting at 4 oC.

Keywords: Escherichia coli, plasmid degradation, cold storage