Little is known about the regulatory mechanisms that ensure the survival of the food-borne bacterial pathogen Listeria monocytogenes in the telluric environment and on roots. Earlier studies have suggested a regulatory overlap between the Agr cell-cell communication system and the general stress response regulator σB. Here, we investigated the contribution of these two systems to root colonisation and survival in sterilised and biotic soil. The ability to colonise the roots of the grass Festuca arundinacea was significantly compromised in the double mutant (∆agrA∆sigB). In sterile soil at 25˚C, a significant defect was observed in the double mutant, suggesting some synergy between these systems. However, growth was observed and similar population dynamics were shown in the parental strain, ΔagrA and ΔsigB mutants. In biotic soil at 25˚C, viability of the parental strain declined steadily over a two-week period highlighting the challenging nature of live soil environments. Inactivation of the two systems further decreased survival. The synergistic effect of Agr and σB was stronger in biotic soil. Transcriptional analysis confirmed the expected effects of the mutations on known Agr- and σB-dependent genes. Data highlight the important role that these global regulatory systems play in the natural ecology of this pathogen.

中文翻译：

---

研究AgrA和σB调节剂在单核细胞增生李斯特菌对根和土壤的适应性中的作用。

关于确保食源性细菌病原体单核细胞增生李斯特氏菌在碲环境和根中存活的调控机制知之甚少。较早的研究表明，Agr细胞-细胞通讯系统与一般应激反应调节剂σB之间存在调节重叠。在这里，我们研究了这两个系统对无菌土壤和生物土壤中根部定植和存活的贡献。在双突变体（ΔagrAΔsigB）中，定植草根草的根的能力显着降低。在25°C的无菌土壤中，在双突变体中观察到明显的缺陷，表明这些系统之间存在一些协同作用。但是，在亲本菌株ΔagrA和ΔsigB突变体中观察到生长并显示出相似的种群动态。在25˚C的生物土壤中，在两个星期的时间内，亲本菌株的生存力稳步下降，突显了活土壤环境的挑战性。两个系统的失活进一步降低了存活率。在生物土壤中，Agr和σB的协同作用较强。转录分析证实了突变对已知的Agr和σB依赖性基因的预期影响。数据突显了这些全球监管系统在该病原体的自然生态中发挥的重要作用。