48 MICROBIAL CELL WALLS 



O-ester Groups. The presence of O-substituents in bac- 

 terial walls was first reported by Abrams,3o who discovered 

 O-acetyl groups in the walls of Streptococcus jae calls and 

 those of several other bacteria. Brumfitt, Wardlaw, and 

 Park ^^ subsequently found that a lysozyme-resistant mutant 

 of Micrococcus lysodeikticus contained a much greater 

 amount of O-acetyl in the walls than the parent strain. 

 Removal of the O-acetyl groups restored the sensitivity to 

 lysozyme. The O-alanyl groups of the teichoic acids are 

 the only other O-ester gioups so far reported in bacterial 

 walls. 



Whether the teichoic acids in Lactobacillus arahinosus 

 are ester linked to other wall components is not known, but 

 it is of interest to note that the lysozyme sensitivity of the 

 isolated walls of this organism is greatly increased after ex- 

 traction with reagents removing O-esters and/or teichoic 

 acid.3^ Armstrong et al.^^ reported that alanine was the 

 only O-ester in the wall of this organism, so it appears that 

 the change in lysozyme sensitivity does not involve removal 

 of O-acetyl groups as in Micrococcus lysodeikticus walls. '^^ 



Composition of Walls of Gram-Negative Bacteria 



The status of our knowledge of the chemistry of the walls 

 of Gram-negative bacteria is less satisfactory, although a 

 clearer picture is beginning to emerge from the detailed 

 studies of Escherichia coli walls by Weidel and his col- 

 leagues. The greater complexity of the walls of Gram-nega- 

 tive bacteria has already been emphasized. ^^-^^ In addition 

 to a complete range of amino acids, they also contain sub- 

 stantial amounts of lipid and frequently a variety of mono- 

 saccharide constituents. The amino sugar contents are 

 generally lower than those found for the majority of walls 

 from Gram-positive bacteria. Some typical analyses for 

 amino sugar contents and amounts of lipid in the walls of 



