College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China; Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, China.
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
Ecotoxicol Environ Saf. 2020 May;194:110441. doi: 10.1016/j.ecoenv.2020.110441. Epub 2020 Mar 7.
Vesicles (Ves) within fungal cells are the critical linkage between intracellular and extracellular systems. This study explored the application of Pb to probe the physiology of intracellular Ves in Rhodotorula mucilaginosa (Rho). At low Pb 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/10 cells and 37 mg C 10 cells h, 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 Pb 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连接。本研究探讨了 Pb 在探测 Rhodotorula mucilaginosa (Rho) 细胞内囊泡生理中的应用。在低 Pb 水平（0-500 mg/L）下，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 显著增大，大量 Pb 纳米颗粒（Pb NPs）形成于细胞表面或内部，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，细胞计数减少超过 99%。然而，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 个细胞和 37 mg C 10 个细胞 h）。与细胞膜相比，囊泡表面吸附的 Pb 阳离子密度更高。此外，在透射电子显微镜（TEM）下观察到一些 Ves 与膜融合（用于运输）。最终提出了三种通过细胞内 Ves 进行解毒的途径，即 EPS 成分通过 Ve 介导的运输（从细胞内到细胞外）、Pb NPs 在 Ve 表面的吸收以及 Pb NPs 在 Ves 内的积累。本研究为通过 Pb 阳离子探索微生物生理学提供了可能性。
