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Abstract

The cell wall of lactic acid bacteria has the typical gram-positive structure made of a thick, multilayered peptidoglycan sacculus decorated with proteins, teichoic acids and polysaccharides, and surrounded in some species by an outer shell of proteins packed in a paracrystalline layer (S-layer). Specific biochemical or genetic data on the biosynthesis pathways of the cell wall constituents are scarce in lactic acid bacteria, but together with genomics information they indicate close similarities with those described in Escherichia coli and Bacillus subtilis, with one notable exception regarding the peptidoglycan precursor. In several species or strains of enterococci and lactobacilli, the terminal D-alanine residue of the muramyl pentapeptide is replaced by D-lactate or D-serine, which entails resistance to the glycopeptide antibiotic vancomycin. Diverse physiological functions may be assigned to the cell wall, which contribute to the technological and health-related attributes of lactic acid bacteria. For instance, phage receptor activity relates to the presence of specific substituents on teichoic acids and polysaccharides; resistance to stress (UV radiation, acidic pH) depends on genes involved in peptidoglycan and teichoic acid biosynthesis; autolysis is controlled by the degree of esterification of teichoic acids with D-alanine; mucosal immunostimulation may result from interactions between epithelial cells and peptidoglycan or teichoic acids.

Lipotechoic acid in lactobacilli: d -Alanine makes the difference

“…Notably, non-protein cell envelope components have been identified as ligands for TLRs, and a well known example is TLR4, which recognizes LPS, a pathogenic determinant present in the cell envelope of Gram-negative bacteria (10). The Gram-positive bacteria that are dominant in the intestinal tract do not contain LPS, but their cell envelope harbors a variety of other polymers, including LTAs (11). LTAs are docked in the cellular membrane by a glycolipid anchor and constitute amphiphilic polymers made up of repeating units of glycerophosphate that are decorated with D-alanine and glycosyl residues (Fig.…”

Peptidoglycan N-acetylglucosamine deacetylation decreases autolysis in Lactococcus lactis

“…Peptidoglycan is the major cell wall component of Grampositive bacteria, and ensures the stability and rigidity of the cell wall (Delcour et al, 1999). During growth, bacteria synthesize enzymes capable of hydrolysing their own peptidoglycan.…”

SpxB Regulates O-Acetylation-dependent Resistance of Lactococcus lactis Peptidoglycan to Hydrolysis

“…It is also responsible for cell shape, participates in cell division, and serves as support for attachment of other cell wall molecules such as teichoic acids, proteins, and exopolysaccharides (3). The bacterial PG is a giant multilayer polymer that envelops the cell as a rigid sacculus.…”