矿区植物根内嗜鱼外瓶霉对重金属的耐性和超积累作用

从云南会泽铅-锌矿区自然生长植物密序野古草(Arundinella bengalensis(Spreng.)Druce)的健康根内分离得到一株深色有隔内生真菌(dark septate endophytes,DSE)。据其形态学特征和ITS1-5.8S-rDNA-ITS2序列分析,鉴定为一株嗜鱼外瓶霉(Exophiala pisciphila)。纯培养条件下研究了其对Pb2+、Zn2+、Cd2+的耐性和超积累作用。结果表明,此菌株在液体合成培养基上可以分别耐受2、3和0.5 g/L的Pb2+、Zn2+和Cd2+;在含Pb2+、Cd2+培养基中生长其菌丝可以富集超过其干重25%以上的Pb2+和5%以上的Cd2+;显示此菌株属于极端耐性并具有超积累作用的真菌。此真菌在植物根系的定殖或许可以通过菌丝体对金属离子的固持作用缓解植物根围土壤微环境中超量金属离子对植物的毒害作用。

Tolerance and accumulation of heavy metals by Exophiala pisciphila strain isolated from plant roots growing in metal polluted soils

A DSE stain was isolated from plant roots of Arundinella bengalensis (Spreng.) Druce, naturally growing on the plot of lead-zinc mine areas in Huize, Yunnan Province. The isolate was identified as an Exophiala pisciphila strain by morphological characteristics and ITS1-5.8S rDNA-ITS 2 sequence analysis. The tolerance to heavy metals and accumulation abilities of the E. pisciphila strain were investigated. MICs (minimum inhibitory concentration) to Pb2+, Zn2+ and Cd2+ of the fungus were 2.3, 0.51, and 3.1 mg/ml, respectively. The E. pisciphila strain was able to accumulate lead, zinc and cadmium over 20%, 15% and 5% of its biomass (by dry weight), respectively. It was demonstrated that the fungi was supper accumulative and multi-tolerant to these metals. Fungi colonization in the roots may play important roles in reducing toxicity to the plant root cells of heavy metals in soils.