用EDTA法研究镰刀菌胞内、胞外Pb2+的分布特征

【目的】建立一种方便、快捷、相对准确、能够定量地测定镰刀菌细胞内、外Pb2+分布的技术手段。【方法】用EDTA溶液浸泡镰刀菌细胞,使其胞外(表面)Pb2+被螯合、洗脱并测定,之后将被浸泡、清洗过的细胞消解、测铅。【结果】EDTA可以将镰刀菌表面的Pb2+螯合,且在99 min内不损伤镰刀菌细胞;以EDTA为反应介质和滴定剂,XO为指示剂,测定镰刀菌胞内、胞外Pb2+分布是可行的。依据此实验方法,测定了镰刀菌在Pb2+浓度为500 mg/L的培养基中的生长曲线、培养基中Pb2+浓度和细胞内、外Pb2+的含量。【结论】镰刀菌固定Pb2+的过程是先将Pb2+吸附在菌体胞外,之后转运至细胞内部,菌体胞外Pb2+的容纳量是有限的,每克菌体胞外Pb2+饱和吸附量约1.37 mg,通过计算可得,每克菌体用于吸附Pb2+的胞外活性位点约3.97×1018个。

Distribution characteristics of intracellular and extracellular lead of strain (Fusarium sp.) determined by EDTA method

Objective] To establish a kind of technology which is able to measure the distribution of the intracellular and extracellular Pb2+ of Fusarium sp.. Methods] Soaked the mycelium pellet in EDTA solution to elute and measure the extracellular Pb2+, then digested the soaked mycelium pellet to measure the intracellular Pb2+. Results] EDTA can elute the extracellular Pb2+, but the cells will not be damaged in 99 minutes; and that it is feasible to measure the concentrations of Pb2+ ions within cells, on the surface of cells and in the medium, with EDTA as reaction medium and titrant and XO as the indicator. On the basis of this experimental method, the growth curve of the strain in medium with 500 mg/L Pb2+ was determined, and the Pb2+ concentrations of medium, and intracellular and extracellular lead contents were measured. Conclusion] Pb2+ will be adsorbed on the surface of cells at first, and then transported into cells. Results show that the Pb2+ adsorbance on the surface of fusaria cells is 1.37 mg/g, and the Pb2+ adsorption site on the surface of fusaria cells are about 3.97×1018/g.