Shao Zongze, Sun Fengqin
Key Lab of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Daxue Road 178#, 361005, Xiamen, Fujian, China.
Extremophiles. 2007 May;11(3):435-43. doi: 10.1007/s00792-006-0051-0. Epub 2007 Jan 31.
A heavy metal resistant fungus was isolated from the sediment of Pacific Ocean, and identified to be Cladosporium cladosporioides. It grew normally in a medium containing 60 mM Mn(2+) and could endure 1,200 mM as the highest concentration tested. Quantification analysis confirmed a high accumulation of Mn which was 58 mg/g in dried biomass. Under transmission electron microscope, many intracellular crystals were observed in the cytoplasm of the hypha cells grown in a Mn-rich medium, and varied from a few nanometers to 200 nm in length. Energy dispersive X-ray (EDX) analysis showed that the crystals were composed of manganese and phosphorus in atomic ratio of 1.6:1 (Mn/P). Further, factors which might influence the resistance of this fungus were investigated. As a result, its high resistance to Mn(2+) was found dependent on the presence of Mg(2+), and could be further enhanced by phosphate. However, the effect of phosphate was not observed without the presence of Mg(2+). In addition, the resistance was also influenced by pH of the medium, which was lost above pH 8. This is the first report on a fungus which showed a hyper resistance to manganese by forming a large quantity of intracellular Mn/P crystals.
从太平洋沉积物中分离出一种耐重金属真菌，经鉴定为枝孢菌。它在含有60 mM Mn(2+)的培养基中能正常生长，在测试的最高浓度1200 mM下也能耐受。定量分析证实其干生物量中锰的积累量很高，为58 mg/g。在透射电子显微镜下，在富含锰的培养基中生长的菌丝细胞的细胞质中观察到许多细胞内晶体，其长度从几纳米到200纳米不等。能量色散X射线（EDX）分析表明，这些晶体由锰和磷组成，原子比为1.6:1（Mn/P）。此外，还研究了可能影响该真菌抗性的因素。结果发现，其对Mn(2+)的高抗性依赖于Mg(2+)的存在，并且磷酸盐可以进一步增强这种抗性。然而，在没有Mg(2+)存在的情况下，未观察到磷酸盐的作用。此外，抗性还受培养基pH值的影响，在pH 8以上抗性丧失。这是关于一种真菌通过形成大量细胞内Mn/P晶体表现出对锰超抗性的首次报道。
