In this study, the cadmium (Cd)-tolerant strain NER9 with quorum sensing (QS) systems (responsible for N-acyl homoserine lactone (AHL) production) was characterized for QS system-mediated Cd immobilization and the underlying mechanisms involved. Whole-genome sequence analysis revealed that strain NER9 contains the QS SinI/R and TraI/R systems. Strains NER9 and the NER9∆, NER9∆, and NER9∆- mutants were constructed and compared for QS SinI/R and TraI/R system-mediated Cd immobilization in the solution and the mechanisms involved. After 24 h of incubation, strain NER9 significantly decreased the Cd concentration in the Cd-contaminated solution compared with the NER9∆, NER9∆, and NER9∆ mutants. The NER9∆ mutant had a greater impact on Cd immobilization and a lower impact on the activities of AHLs than did the NER9∆ mutant. The NER9∆ mutant had significantly greater Cd concentrations and lower cell wall- and exopolysaccharide (EPS)-adsorbed Cd contents than did strain NER9. Furthermore, the NER9∆ mutant presented a decrease in the number of functional groups interacting with Cd, compared with strain NER9. These results suggested that the SinI/R system in strain NER9 contributed to Cd immobilization by mediating cell wall- and EPS-adsorption in Cd-containing solution.

中文翻译：

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群体感应 SinI/R 系统有助于在镉污染溶液中的 Ensifer adhaerens NER9 中固定镉

在本研究中，对具有群体感应 (QS) 系统（负责 N-酰基高丝氨酸内酯 (AHL) 生产）的镉 (Cd) 耐受菌株 NER9 进行了 QS 系统介导的 Cd 固定化及其相关机制的表征。全基因组序列分析显示菌株NER9含有QS SinI/R和TraI/R系统。构建了菌株 NER9 和 NER9Δ、NER9Δ 和 NER9Δ- 突变体，并比较了溶液中 QS SinI/R 和 TraI/R 系统介导的 Cd 固定以及所涉及的机制。孵育 24 小时后，与 NER9Δ、NER9Δ 和 NER9Δ 突变体相比，菌株 NER9 显着降低了 Cd 污染溶液中的 Cd 浓度。与 NER9Δ 突变体相比，NER9Δ 突变体对 Cd 固定的影响更大，对 AHL 活性的影响较小。与菌株 NER9 相比，NER9Δ 突变体具有显着更高的 Cd 浓度和更低的细胞壁和胞外多糖 (EPS) 吸附的 Cd 含量。此外，与菌株 NER9 相比，NER9Δ 突变体与 Cd 相互作用的功能团数量减少。这些结果表明，NER9 菌株中的 SinI/R 系统通过介导含 Cd 溶液中的细胞壁和 EPS 吸附来促进 Cd 固定。