Distribution of muropeptides in walls of Bacillus subtilis and a temperature-sensitive mutant

Attempts to correlate differences in cell shape with aspects of peptidoglycan structure were investigated. The parent strain, Bacillus subtilis 168, and its temperature-sensitive tagB mutant were grown in the chemostat under different growth conditions. The composition of the peptidoglycan was similar in all samples, regardless of cellular shape and anionic polymer content. Muropeptides, released by digestion with muramidase, comprised mainly dimers and monomers with only small amounts of trimer and traces of tetramer muropeptide. Overall, cross-linking did not vary greatly and the cross-linking index was less than 38%. Reverse-phase HPLC separation showed a complex fine structure. The principal muropeptides in all samples appeared to be the tetra monomer, tetra-tetra dimer and tetra-tetra-tetra trimer. While the major components looked the same in all samples, two specific components, a monomer and a dimer, were seen exclusively in the samples that had coccal morphology.