Many antibiotics and antimicrobial agents have the bacterial cell envelope as their primary target, interfering with functions such as synthesis of peptidoglycan, membrane stability and permeability, and attachment of surface components. The cell envelope is the outermost barrier of the bacterial cell, conferring protection against environmental stresses, and maintaining structural integrity and stability of the growing cell, while still allowing for required metabolism. In this work, inhibitory concentrations of several different cell envelope targeting antibiotics and antimicrobial agents were used to select for derivatives of lactic acid bacteria (LAB) with improved properties for dairy applications. Interestingly, we observed that for several LAB species a fraction of the isolates had improved milk texturizing capabilities. To further improve our understanding of the mechanisms underlying the improved rheology and to validate the efficacy of this method for strain improvement, genetic and physiological characterization of several improved derivatives was performed. The results showed that the identified genetic changes are diverse and affect also other cellular functions than the targeted cell surface. In short, this study describes a new versatile and powerful toolbox based on targeting of the cell envelope to select for LAB derivatives with improved phenotypic traits for dairy applications.

中文翻译：

---

使用细胞包膜靶向抗生素和抗微生物剂作为在牛奶发酵中选择具有改进的组织化能力的乳酸菌菌株的有力工具

许多抗生素和抗菌剂以细菌细胞包膜为主要靶点，干扰肽聚糖的合成、膜稳定性和渗透性以及表面成分的附着等功能。细胞包膜是细菌细胞的最外层屏障，提供抵御环境压力的保护，并保持生长细胞的结构完整性和稳定性，同时仍允许进行所需的新陈代谢。在这项工作中，几种不同的细胞包膜靶向抗生素和抗微生物剂的抑制浓度用于选择乳酸菌 (LAB) 的衍生物，这些衍生物具有改进的乳制品应用特性。有趣的是，我们观察到，对于几个 LAB 物种，一小部分分离株具有改善的牛奶质地能力。为了进一步提高我们对改进流变学基础机制的理解，并验证该方法对菌株改进的功效，对几种改进的衍生物进行了遗传和生理表征。结果表明，鉴定出的遗传变化是多种多样的，并且还影响目标细胞表面以外的其他细胞功能。简而言之，这项研究描述了一种新的多功能且强大的工具箱，该工具箱基于细胞包膜的靶向，以选择具有改善的表型特征的 LAB 衍生物，用于乳制品应用。结果表明，鉴定出的遗传变化是多种多样的，并且还影响目标细胞表面以外的其他细胞功能。简而言之，这项研究描述了一种新的多功能且强大的工具箱，该工具箱基于细胞包膜的靶向，以选择具有改进表型特征的 LAB 衍生物，用于乳制品应用。结果表明，鉴定出的遗传变化是多种多样的，并且还影响目标细胞表面以外的其他细胞功能。简而言之，这项研究描述了一种新的多功能且强大的工具箱，该工具箱基于细胞包膜的靶向，以选择具有改善的表型特征的 LAB 衍生物，用于乳制品应用。