Lactic acid bacteria (LAB) are important starter, commensal, or pathogenic microorganisms. The stress physiology of LAB has been studied in depth for over 2 decades, fueled mostly by the technological implications of LAB robustness in the food industry. Survival of probiotic LAB in the host and the potential relatedness of LAB virulence to their stress resilience have intensified interest in the field. Thus, a wealth of information concerning stress responses exists today for strains as diverse as starter (e.g., Lactococcus lactis), probiotic (e.g., several Lactobacillus spp.), and pathogenic (e.g., Enterococcus and Streptococcus spp.) LAB. Here we present the state of the art for LAB stress behavior. We describe the multitude of stresses that LAB are confronted with, and we present the experimental context used to study the stress responses of LAB, focusing on adaptation, habituation, and cross-protection as well as on self-induced multistress resistance in stationary phase, biofilms, and dormancy. We also consider stress responses at the population and single-cell levels. Subsequently, we concentrate on the stress defense mechanisms that have been reported to date, grouping them according to their direct participation in preserving cell energy, defending macromolecules, and protecting the cell envelope. Stress-induced responses of probiotic LAB and commensal/pathogenic LAB are highlighted separately due to the complexity of the peculiar multistress conditions to which these bacteria are subjected in their hosts. Induction of prophages under environmental stresses is then discussed. Finally, we present systems-based strategies to characterize the "stressome" of LAB and to engineer new food-related and probiotic LAB with improved stress tolerance.

中文翻译：

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乳酸菌的应激生理。

乳酸菌（LAB）是重要的发酵菌，共生菌或致病微生物。LAB的应力生理学已被深入研究了20多年，其主要原因是LAB健壮性在食品行业中的技术意义。益生菌LAB在宿主中的存活以及LAB毒力与其应激抗性的潜在相关性引起了人们对该领域的兴趣。因此，如今对于各种菌株，如起子（如乳酸乳球菌），益生菌（如几种乳杆菌属）和致病性（如肠球菌和链球菌）LAB，存在大量有关应激反应的信息。在这里，我们介绍了LAB应力行为的最新技术。我们描述了LAB面临的众多压力，我们提供了用于研究LAB的应力响应的实验环境，重点是适应性，适应性和交叉保护以及固定相，生物膜和休眠中的自诱导多应力抗性。我们还考虑了群体和单细胞水平的应激反应。随后，我们集中于迄今为止已报道的压力防御机制，根据它们直接参与保存细胞能量，防御大分子和保护细胞包膜的方式将它们分组。由于这些细菌在其宿主中所处的特殊多应激条件的复杂性，分别强调了益生菌LAB和共生/致病性LAB的应激诱导反应。然后讨论了在环境压力下的预言归纳。最后，