Abstract
The thymidylate synthetase gene of B. subtilis bacteriophage Phi-3-T, when cloned in plasmids pSC101 or pMB9 is expressed in E. coli. The promoter of the cloned gene is likely to originate in Phi-3-T. Rearrangements of hybrid plasmid sequences during the cloning have been noted. B. subtilis strains can be transformed with hybrid DNAs. The transformants contain sequences of Phi-3-T, but not those of plasmid vectors.