Occurrence of glucosamine residues with free amino groups in cell wall peptidoglycan from bacilli as a factor responsible for resistance to lysozyme.

Analysis by dinitrophenylation techniques revealed the occurrence of significant amounts of glucosamine residues with free amino groups in the peptidoglycan component of cell walls isolated from Bacillus cereus, Bacillus subtilis, and Bacillus megaterium. A close correlation was demonstrated between the content of N-unacetylated glucosamine residues in the peptidoglycan component and the resistance of the cell walls to lysozyme. These lysozyme-resistant cell walls and peptidoglycan were converted into a lysozyme-sensitive form by means of N-acetylation with acetic anhydride. Thus, the occurrence of the N-unacetylated glucosamine residues in the peptidoglycan component accounts for the resistance of these cell walls to lysozyme. The N-unacetylated glucosamine residues were not found in a significant amount in the cell walls of Micrococcus lysodeikticus, Staphylococcus aureus, Streptococcus faecalis, Lactobacillus casei, or Lactobacillus arabinosus.