I am searching for a distributor or collection of E. coli strains that offer classical strains for cloning (DH10b, DH5a, Rosetta, etc) to set up a reliable collection for cloning and classical molecular biology. Could you help me?
You may request the author of a recent published paper using these E. coli strains to gift you culures for research. Or procure from ATCC, USA or NCIMB, Aberdeen, UK if funds are available with your lab.
However, even if these are reputable culture collection centers, I would double-check the strains upon arrival (grow & sequence). Mistakes can happen everywhere, which is why I would generally recommend to check any new strains you receive as this might save you a lot of frustration, money and time.