The quorum-sensing (QS) system in Rhizobiaceae has been studied, however, the mechanisms of QS system-mediated mineral dissolution by bacteria remain poorly understood. Here, the mineral-solubilizing Agrobacterium pusense SX41 harboring the QS system (responsible for N-acyl homoserine lactone (AHL) production) was characterized for QS system-mediated Al and Fe release from biotite. Whole-genome sequence analysis revealed that SX41 contains the QS TraI/TraR system. SX41 and the SX41∆traI, SX41∆traR, and SX41∆traI/R mutants were constructed from SX41 and compared for QS TraI/R system-mediated Fe and Al release from biotite in the solution and the underlying mechanisms. The SX41∆traI, SX41∆traR, and SX41∆traI/R mutants significantly decreased the Al and Fe concentrations in the medium by 24 % to 54 % on day 1 and 25 % to 42 % on day 5, while these mutants significantly reduced exopolysaccharide (EPS) concentrations in the medium by 21 % to 55 % on day 5, compared with those of SX41. Furthermore, these mutants demonstrated decreased cell counts and biofilm formation on biotite surfaces compared with SX41. Notably, the SX41∆traR mutant exhibited more pronounced effects on Al and Fe release from biotite, EPS production, and cell adsorption and biofilm formation on biotite surfaces compared with the SX41∆traI mutant. Moreover, the addition of biotite significantly upregulated the expression of traI and traR in SX41 and the complemented strains SX41∆traIR and SX41∆traRR. These findings underscore the pivotal role of the TraI/R system in the interactions between SX41 and biotite and highlight the distinct influences of traI and traR on Al and Fe release from biotite by SX41.

中文翻译：

---

群体感应 TraI/TraR 系统有助于农杆菌 SX41 从黑云母中释放 Fe 和 Al


人们已经研究了根瘤菌科的群体感应（QS）系统，然而，细菌介导的 QS 系统介导的矿物质溶解机制仍知之甚少。在此，对含有 QS 系统（负责 N-酰基高丝氨酸内酯 (AHL) 生产）的矿物溶解农杆菌 pusense SX41 进行了 QS 系统介导的黑云母 Al 和 Fe 释放的表征。全基因组序列分析表明SX41含有QS TraI/TraR系统。 SX41 和 SX41ΔtraI、SX41ΔtraR 和 SX41ΔtraI/R 突变体是从 SX41 构建的，并比较了 QS TraI/R 系统介导的溶液中黑云母 Fe 和 Al 的释放以及潜在机制。 SX41ΔtraI、SX41ΔtraR 和 SX41ΔtraI/R 突变体使培养基中的 Al 和 Fe 浓度在第 1 天显着降低 24% 至 54%，在第 5 天显着降低 25% 至 42%，而这些突变体显着降低与 SX41 相比，第 5 天培养基中的胞外多糖 (EPS) 浓度降低了 21% 至 55%。此外，与 SX41 相比，这些突变体表现出黑云母表面的细胞计数和生物膜形成减少。值得注意的是，与SX41ΔtraI突变体相比，SX41ΔtraR突变体对黑云母中Al和Fe的释放、EPS的产生以及黑云母表面的细胞吸附和生物膜形成表现出更显着的影响。此外，黑云母的添加显着上调了 SX41 以及补充菌株 SX41ΔtraIR 和 SX41ΔtraRR 中 traI 和 traR 的表达。这些发现强调了 TraI/R 系统在 SX41 和黑云母相互作用中的关键作用，并强调了 traI 和 traR 对 SX41 从黑云母中释放 Al 和 Fe 的独特影响。