Vesicles (Ves) within fungal cells are the critical linkage between intracellular and extracellular systems. This study explored the application of Pb²⁺ to probe the physiology of intracellular Ves in Rhodotorula mucilaginosa (Rho). At low Pb²⁺ levels (0–500 mg/L), there was no evident change in the content of extracellular polymeric substances (EPS) or microbial activity. At medium-high levels (1000–2000 mg/L), the sizes of Ves within the Rho cells were significantly enlarged, with abundant lead nano-particles (Pb NPs) formed either on the cell surface or interior, whereas the EPS content and bioactivity were still stable. At a high level (2500 mg/L), the Rho cells were severely deformed, with cell counts reduced by more than 99%. However, the EPS contents and the respiration rate of the surviving cells dramatically increased to the maximum values (i.e., 1785 mg/10¹⁰ cells and 37 mg C 10⁻¹⁰ cells h⁻¹, respectively). The Ves surface adsorbed Pb cations with higher density, compared with the cell membrane. Moreover, fusion of some Ves to the membrane (functioning in transport) was observed under transmission electron microscope (TEM). Three pathways of detoxification via intracellular Ves were finally proposed, i.e., Ve-mediated transport (from intracellular to extracellular) of EPS components, absorption of Pb NPs on the Ve surface, and accumulation of Pb NPs within Ves. This study sheds light on the possibility of exploring microbial physiology via Pb²⁺ cations.

真菌细胞内的囊泡（Ves）是细胞内和细胞外系统之间的关键联系。本研究探索了Pb ²⁺在探测粘液红假单胞菌（Rhodotorula mucilaginosa（Rho））中细胞内Ves生理的应用。低铅²⁺浓度（0–500 mg / L）时，细胞外聚合物（EPS）的含量或微生物活性没有明显变化。在中高水平（1000-2000 mg / L）下，Rho细胞内的Ves大小显着增大，在细胞表面或内部形成大量的铅纳米颗粒（Pb NPs），而EPS含量和生物活性仍然稳定。在高水平（2500 mg / L）下，Rho细胞严重变形，细胞数减少了99％以上。但是，存活细胞的EPS含量和呼吸速率急剧增加到最大值（即1785 mg / 10 ¹⁰ 细胞和37 mg C 10 ^-10 细胞h ^-1， 分别）。与细胞膜相比，Ves表面以更高的密度吸附了Pb阳离子。此外，在透射电子显微镜（TEM）下观察到一些Ves融合到膜上（在运输中起作用）。最后提出了通过细胞内Ves解毒的三种途径，即EPS成分的Ve介导运输（从细胞内到细胞外），Ve表面上Pb NP的吸收以及Ves内Pb NP的积累。这项研究揭示了通过Pb ²⁺阳离子探索微生物生理的可能性。