Peptidoglycan layer, Gram-negative

The complex outer layers beyond the peptidoglycan in the Gram-negative species, the outer membrane, protect the organism to a certain extent from the action of toxic chemicals (see Chapter 13). Thus, disinfectants are often effective only at concentrations higher than those affecting Gram-positive cells and these layers provide unique protection to the cells from the action of benzylpenicillin and lysozyme. 

Gram-negative bacteria have a more complex cell surface. The peptidoglycan layer is also the outer layer with respect to the cytoplasmic membrane. However, besides this, they have another outer polysaccharide membrane. This outer membrane is built out of lipopolysac-charides and lipoproteins, and can be a serious barrier for permeating hydrophilic molecules. 

Gram-negative tougher peptidoglycan layer extensive internal membrane system with photosynthetic pigments... 

The outer surfaces of bacteria are rich in specialized polysaccharides. These are often synthesized while attached to lipid membrane anchors as indicated in a general way in Eq. 20-20.136/296a One of the specific biosynthetic cycles (Fig. 20-9) that depends upon undeca-prenol phosphate is the formation of the peptidoglycan (murein) layer (Fig. 8-29) of both gram-negative and gram-positive bacterial cell walls. Synthesis begins with attachment of L-alanine to the OH of the lactyl... 

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