Hi The original E. coli DB3.1 strain is available via the BCCM/GeneCorner Plasmid Collection http://bccm.belspo.be/ Email: [email protected]
Life Technologies indeed provides the One Shot ccdB survival strain as an alternative, however we've noticed this strain doesn't work equally well for all plasmids. With the DB3.1 strain, so far we never had any issues.
The DB3.1 strain has collection number 4098 and is listed on page