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.

Suggestions:

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
sequencing.