[Stress-induced breakdown of chained cells in Bacillus subtilis filaments]

Triple auxotroph of Bacillus subtilis 168 grew as chains of unseparated cells of normal morphology at 30 degrees C. The strain displayed reduced competence for DNA-mediated transformation and showed strong interbacterial aggregation in liquid media. On the solid media the colonies had a typical rough appearance. Environmental stresses (heat shock, UV light, gamma-rays, and methylating agent) resulted in gradual dechaining during extended incubation of the bacteria in the static liquid medium with or without required amino acids at room temperature. Simultaneously with this process, the suspensions of cells acquired homogeneity and a new pattern of electrophoretic mobility. These phenomena may be interpreted in terms of stress-inducible RS-dissociation. Alternative explanations are also discussed.