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.

中文翻译：

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乳酸菌中的细胞壁稳态：威胁与防御。

乳酸菌（LAB）包括与食品发酵有关的与工业相关的细菌，以及我们自生微生物群中促进健康的成员。在过去的几年中，我们目睹了它们细胞壁生物学知识的重大进步，革兰氏阳性细胞的最外层宏观结构对生存至关重要。复杂的生化分析与突变策略相结合已被用于揭示维持LAB内物种间和物种内细胞壁多样性的生物合成途径。与全局细胞代谢的相互作用已被解密，从而增进了我们对生长过程中细胞壁可塑性的基本了解。细胞壁对于许多细菌素的抗菌活性也起着决定性作用，用于噬菌体感染以及与外部环境的相互作用。因此，在LAB中已经描述了与监测细胞壁损伤有关的遗传回路，以及大量的防御机制，这些机制可帮助它们应对外部威胁并适应恶劣条件。由于细胞壁在LAB的几个技术和促进健康的特性中起着关键作用，因此我们预计，这些知识将为LAB的未来开发和扩展应用铺平道路。