Effect of salt on a thermosensitive mutant of Bacillus subtilis deficient in uracil and cell division

A thermosensitive mutant ts 42, of Bacillus subtilis Marburg 168 thy trp2 which requires uracil, was examined as to the colony-forming ability at the permissive and nonpermissive temperatures. The viability of the mutant cells decreased rapidly at the restrictive temperature in modified woese's medium. However, the cells retained the viability when sodium succinate or potassium chloride was added to the medium at that temperature, although uranil deficiency was unchanged. A little but significant incorporation of adenine-8-14C into RNA still continued even after the incorporation of N-acetyl-3H-D-glucosamine into the acid-insoluble fraction of the cells terminated in the modified Woese's medium at 480C. Both incorporations as well as the increase of absorbance were slowed down in the presence of sodium succinate at 480C. This mutant, ts42, was more sensitive to deoxycholate than the parent wild strain. The resoration of the colony-forming ability after the temperature shifted back from 480 to 370C was suppressed by the addition of deoxycholate to the medium. However, the cells became resistant to deoxycholate when uracil had been added to the medium prior to the temperature shift. (Kobatake, H.)