Detergent-resistant variants of Bacillus subtilis with reduced cell diameter

Abstract

Variants of Bacillus subtilis resistant to the detergent Triton X-100 may exhibit: (i) normal cell morphology, (ii) reduced cell diameter, or (iii) helical cell shape. One variant of type ii was studied in some detail. Triton resistance, cell diameter reduction, and poor sporulation all may have resulted from a single mutation. High concentrations of Triton caused rapid lysis of wild-type cells. B. subtilis adapted to low Triton concentrations such that, upon subsequent exposure to higher concentrations, growth continued, although it bacame inhibited at very high concentrations. The variant studied retained its sensitivity to Triton-induced lysis but, after adaptation, grew at very high Triton levels. In this strain, cell diameter and cross-sectional area were reduced to about 73 and 50%, respectively, of those of wild type, yet the cells grew at normal rates, and DNA/protein/RNA ratios were largely unaltered. Peptidoglycan content per unit of cell surface area was higher in the variant than in the wild type under at least certain growth conditions.