Stbl3 strain may be difficult to sequence directly from colonies

EndA+ strain used. Certain strains of E. coli (e.g. BL21, Stbl3) contain a non-specific endonuclease in the periplasmic space that can cleave plasmid DNA
when cells are lysed, leading to inefficient amplification.


1. Use a strain with the endA mutation (e.g. DH5α, TOP10).
2. Prep the DNA and submit purified plasmids.
3. Use PCR to amplify the region of interest and submit PCR products for