Characterization of intracellular deoxyribonucleases of Bacillus subtilis by SDS-polyacrylamide gel electrophoresis

Electrophoresis in polyacrylamide gels containing DNA was used to study nucleolytic activities in Bacillus. Optimal conditions (cations, pH and substrate) and a general pattern of DNases of B. subtilis 168 were established, revealing the presence of twelve to fourteen defined bands with DNase activity. Fractionation of cell cultures showed that most of the nucleases were located in the bacterial cytosol, and only two activities were membrane-associated. The employment of plasmid DNA in the gels facilitated distinguishing between exo- and endonucleases, the latter being the most active bands. The DNase pattern of various strains of B. subtilis, and species of the genus Bacillus, was compared. Evident differences were observed although similarities exist.