Cell wall homeostasis in lactic acid bacteria: threats and defences

Abstract

Lactic acid bacteria (LAB) encompasses industrially relevant bacteria involved in food fermentations as well as health-promoting members of our autochthonous microbiota. In the last years, we have witnessed major progresses in the knowledge of the biology of their cell wall, the outermost macrostructure of a Gram-positive cell, which is crucial for survival. Sophisticated biochemical analyses combined with mutation strategies have been applied to unravel biosynthetic routes that sustain the inter- and intra-species cell wall diversity within LAB. Interplay with global cell metabolism has been deciphered that improved our fundamental understanding of the plasticity of the cell wall during growth. The cell wall is also decisive for the antimicrobial activity of many bacteriocins, for bacteriophage infection and for the interactions with the external environment. Therefore, genetic circuits involved in monitoring cell wall damage have been described in LAB, together with a plethora of defence mechanisms that help them to cope with external threats and adapt to harsh conditions. Since the cell wall plays a pivotal role in several technological and health-promoting traits of LAB, we anticipate that this knowledge will pave the way for the future development and extended applications of LAB.

Bacillus amyloliquefaciens and Saccharomyces cerevisiae feed supplements improve growth performance and gut mucosal architecture with modulations on cecal microbiota in red-feathered native chickens

“…These results showed the participation of cecal featured taxa in metabolic functions. The peptidoglycan as a macromolecular component of the bacterial cell wall maintains the shape and integrity of the cell and forms a thick layer in the cell wall of lactic acid bacteria (LAB) [ 47 ]. LAB strains, Lactobacillus in particular, are commercially used as probiotics with health or growth-promoting properties [ 48 ].…”

Proteomic Analysis Reveals Enzymes for β-D-Glucan Formation and Degradation in Levilactobacillus brevis TMW 1.2112

“…Though changes in the heterogeneous character of the viscosity might be attributed to the formation of a β-glucan-cell-network, lysed cells reduced the network integrity during the late stationary and early death phases, and this in turn might have led to the reduced viscosity [ 34 , 35 ]. Autolysis, which is strain-dependent and preferentially triggered under stress conditions or in late growth phases, is a well-known phenomenon in lactic acid bacteria [ 91 , 92 ]. Moreover, the increased number of proteins in the secretome after 7 days compared to 8 h could also be explained by the autolysis of L. brevis TMW 1.2112 cells.…”

Biodetoxification and Protective Properties of Probiotics

“…The second is when probiotics and strains can mitigate the carcinogenic danger through their metabolism. The cell wall of probiotics is primarily composed of peptidoglycan found in glycan chains consisting of alternating N-needles tilglucosamine and N-2 acetylmuramic acid, linked by β-1,4 bond [ 74 ].…”