How do I know if my plasmid is a high- or low copy number type?

Find out which origin of replication your plasmid contains, and look at the table below for classification into high-copy or low-copy types. This table can also be found online at the QIAGEN Plasmid Resource Center in the section 'Growth of bacterial cultures; Plasmid Copy Number' . A way to determine experimentally if the copy number of your plasmid is high or low is to perform a miniprep. A high-copy plasmid should yield between 3-5 ug DNA per 1 ml LB culture, while a low-copy plasmid will yield between 0.2-1 ug DNA per ml of LB culture.

 

Origins of replication and copy numbers of various plasmids and cosmids

DNA construct	Origin of Replication	Copy number	Classification
Plasmids
pUC vectors	pMB1*	500–700	high copy
pBluescript® vectors	ColE1	300–500	high copy
pGEM® vectors	pMB1*	300–400	high copy
pTZ vectors	pMB1*	>1000	high copy
pBR322 and derivatives	pMB1*	15–20	low copy
pACYC and derivatives	p15A	10–12	low copy
pSC101 and derivatives	pSC101	~5	very low copy
Cosmids
SuperCos	pMB1*	10-20	low copy
pWE15	ColE1	10-20	low copy

* The pMB1 origin of replication is closely related to that of ColE1 and falls in the same incompatibility group. The high-copy plasmids listed here contain mutated versions of this origin.