Lehrstuhl für Technische Mikrobiologie, Technische Universität München, Freising, Germany.
Leibniz-Institut für Lebensmittel-Systembiologie, Technische Universität München, Freising, Germany.
J Appl Microbiol. 2019 May;126(5):1480-1495. doi: 10.1111/jam.14224. Epub 2019 Mar 18.
Coagulase-negative Staphylococcus xylosus strains are used as starter organisms for sausage fermentation. As those strains have to cope with low pH-values during fermentation, the aim of this study was to identify the acid adaptation mechanisms of S. xylosus TMW 2.1523 previously isolated from salami.
A comparative proteomic study between two different acid tolerant mutants was performed. Therefore, both S. xylosus mutants were grown pH-static under acid stress (pH 5·1) and reference conditions (pH 7·0). Proteomic data were supported by metabolite and cell membrane lipid analysis. Staphylococcus xylosus acid stress adaptation is mainly characterized by a metabolic change towards neutral metabolites, enhanced urease activity, reduced ATP consumption, an increase in membrane fluidity and changes in the membrane thickness.
This study corroborates mechanisms as previously described for other Gram-positive bacteria. Additionally, the adjustment of membrane structure and composition in S. xylosus TMW 2.1523 play a prominent role in its acid adaptation.
This study demonstrates for the first time changes in the membrane lipid composition due to acid stress adaptation in staphylococci.
凝固酶阴性葡萄球菌（Coagulase-negative Staphylococcus）菌株被用作香肠发酵的起始生物。由于这些菌株在发酵过程中必须应对低 pH 值，因此本研究的目的是鉴定先前从意大利萨拉米香肠中分离出的 S. xylosus TMW 2.1523 的酸适应机制。
对两种不同耐酸突变体进行了比较蛋白质组学研究。因此，两种 S. xylosus 突变体均在 pH 静态下在酸性胁迫（pH 5.1）和参考条件（pH 7.0）下生长。蛋白质组学数据得到了代谢物和细胞膜脂质分析的支持。葡萄球菌的酸应激适应主要表现为向中性代谢物的代谢变化、增强的脲酶活性、降低的 ATP 消耗、膜流动性增加以及膜厚度的变化。
本研究证实了先前在其他革兰氏阳性菌中描述的机制。此外，S. xylosus TMW 2.1523 中膜结构和组成的调整在其酸适应中起着重要作用。
本研究首次证明了葡萄球菌因酸应激适应而导致膜脂组成发生变化。
