SUMMARY: Cell walls were prepared from: (1) 8081 grown (in partly defined medium) without methicillin; (2) 8081 grown with a sub-inhibitory concentration of methicillin (10 µg./ml.); (3) 8081 CRD (methicillin-dependent substrain) grown with an optimal concentration of methicillin (100 µg./ml.). All three preparations contained glucosamine, muramic acid, -acetyl groups (no -acetyl groups), alanine. glutamic acid, lysine and aspartic acid, in proportions which suggested that they were components of a mucopeptide polymer; small amounts of serine. glycine and threonine were also present. The mucopeptide components made up about 50% by weight of walls (1) and (2) but about 80% in walls (3). Glucose and phosphorus were present in the walls, in greater amounts in walls (1) and (2) than in walls (3). No free amino groups were detected in any of the walls, and most of the lysine was released as ε-(aminosuccinyl)-lysine when mucopeptide from the parent strain was hydrolysed for a short period. About 35% of walls (1) and (2) was removed by extraction at 2: with trichloroacetic acid; only 16% was removed from walls (3). Nearly all the glucose and most of the phosphorus was removed from all the walls by such extraction; the residues after extraction all contained about 90% of mucopeptide components. Teichoic acids were isolated from each trichloroacetic acid extract: phosphorus, glucose, alanine and glycerol were found in all. Teichoic acid from walls (3) contained, in addition, about 7% of mucopeptide components. Walls and trichoroacetic acid insoluble residues from the methicillin-dependent substrain were hydrolysed much more rapidly by lysozyme than were walls or residues of the parent strain, whether grown in absence or presence of methicillin.


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