一株茎点霉菌的抗镉机制

The cadmium resistance mechanisms of Phoma strain.

从矿区土壤筛选到一株对镉具有较强抗性和富集能力的丝状真菌,编号为F2,根据其形态主要是分生孢子器的特征鉴定为茎点霉菌.对不同镉浓度液体培养下菌体的生长及培养液的pH值变化作了分析,利用扫描电镜、透射电镜与能谱分析相结合的方法研究镉在F2胞内外的沉积作用及分布情况,从而分析该菌对镉的抗性和富集机制.结果表明,100mg/L的镉浓度下,在细胞壁及周围区域存在大量颗粒状镉沉积物,而在菌体表面也有沉淀物附着.因此胞内外沉积作用可能是该菌对高浓度镉的抗性和富集作用的重要途径,而且因为该菌生长过程中尤其是高镉浓度下pH值的大幅度上升,沉积过程可能与该菌在生长过程中产生碱性物质有关.

One strain of filamentous fungi possessing stronger resistance and accumulation abilities was screened from mine soil and numbered as phoma sp. F2. According to its characteristics of morphology being mainly the characteristics of pycnidium, it was identified as phoma fungi. Growth of F2 and pH value change of culture liquid were analyzed under culture liquid of different cadmium concentrations; and the cadmium precipitation and distribution outside and inside the cell were studied using combined technique of scanning electron microscopy (SEM) observation, transmission electron microscopy (TEM) observation and energy dispersive X-ray analysis (EDXA). Under the cadmium concentration of 100mg/L, there were much granular cadmium precipitate on the cell wall and surrounding area, and also precipitate adhering to the surface of the mycelium; therefore, precipitation inside and outside the cell might be an important way of cadmium resistance and accumulation of the fungi, and the precipitation might be related to the production of alkaline materials during the growth process of the fungi due to great increase of pH value in the growth process, especially in the high concentration of cadmium.