Studies of the bacterial cell wall: III. Preliminary investigation of the chemical constitution of the cell wall of Streptococcus faecalis

Abstract

Pure cell walls of Strep. faecalis were prepared in four separate batches. The total P and total N contents of each batch showed sufficiently good agreement to justify pooling. A total yield of 1.5 g was obtained, representing a yield of 5% of the dry weight of the bacteria used. 1. 1. Some general properties (including qualitative and solubility tests) of the cell wall preparation have been recorded. 2. 2. The rate of hydrolysis of the cell wall material with 2 N hydrochloric acid at 100°C has been followed. The material is rapidly hydrolysed, with liberation of reducing substances, hexosamine and inorganic phosphate. 3. 3. The cell wall contains 1.88% P; 5.6% N and 0.3% S. Lipoid material to the extent of 2.3% has been extracted. Reducing substances amount to 61.4% (expressed as glucose) on hydrolysis. The cell wall contains 22.2% hexosamine. 4. 4. Fractionation of the cell wall complex has been attempted by treatment with 90% phenol, 0.1 N sodium hydroxide, and hydrolysis with 0.1 N acetic acid and with 0.01 N hydrochloric acid. Mild acid hydrolysis has effected a marked degradation in the constitution of the complex. 5. 5. The sugars present in the cell wall preparation have been identified by paper chromatography as: galactose, glucose and rhamnose, together with an amino-sugar, hexosamine. 6. 6. The amino-acids identified by paper chromatography are: aspartic acid, glutamic acid, serine, glycine, threonine, alanine, lysine, valine and/or methionine and leucine. Alanine, glutamic acid and lysine are present in much greater amounts than the other amino-acids. One or possibly two unknown ninhydrin-reacting substances were present in the cell wall hydrolysate.