Measurement of pyrimidine dimers in spheroplasts of Bacillus subtilis.

A method is described for making spheroplasts of Bacillus subtilis which are permeable to exogenous enzymes. Conditions are described for measuring small numbers of pyrimidine dimers in the DNA of UV-irradiated cells by use of a partially purified Micrococcus luteus extract containing an enzyme specific for pyrimidine dimers. The system will detect as few as 10-12 pyrimidine dimers per genome.