Screening,Identification,Metal-tolerance Cadmium Biosorption and Application of a Cadmium-Resistant Trichoderma asperellum

耐镉棘孢木霉的筛选鉴定及其镉吸附特性（英文）

This study was designed to screen and identify cadmium-resistant fungi and characterize its cadmium adsorption.A cadmium-resistant strain(HD228)was isolated from cadmium-polluted paddy soil by using the Cd^2+concentration gradient pressure domestication method.According to the morphological characteristics and the analysis of internal transcribed spacers(ITS)region gene sequence phylogenesis,the strain was identified as Trichoderma asperellum.This strain was resistant to Cd at 22 mmol/L with a Cd adsorption rate of up to 79.88%,and it was also resistant to other heavy metals such as Pb,Zn and Cu.The colony diameter decreased as the heavy metal concentration increased,and the colony was out-of-shape when the Cd^2+concentration was 20 mmol/L.The strain HD228 was found to grow well at pH 4 to 8 and a temperature between 20 and 35℃.The optimal growth conditions were established to be pH 5 and temperature of 30℃.Fermented liquid of the strain is neither disease-causing nor inhibitory to rice seedling emergence,and indeed it improves rice seedling and root growth and enhances rice’s detoxification ability under Cd stress.Thus,the Cd-resistant fungus HD228 has the potential for the treatment of Cd-polluted rice paddies.

为筛选鉴定耐镉真菌及研究其镉吸附特性,采用Cd^(2+)浓度梯度压力驯化法从镉污染稻田土壤中分离到耐镉菌株HD228,综合菌株形态特征、ITS基因序列系统进化分析,鉴定其为棘孢木霉(Trichoderma asperellum)。结果表明,该菌株耐22 mmol/L Cd,对Cd的吸附率可达79.88%,对Pb、Zn、Cu具有很强耐性,Pb、Zn、Cu对HD228的最低抑制浓度(MIC)分别为>80 mmol/L、>80 mmol/L、>30 mmol/L;菌落直径与重金属浓度呈负相关,20 mmol/L时菌落不规则;能在pH值4～8、温度20～35℃条件下良好生长,最适生长和耐镉pH值为5、温度为30℃,温度和pH值均不影响其耐镉能力;其发酵液对水稻出苗、幼苗生长无抑制作用,发酵液40 mL(200 g土)用量对水稻具有促生作用,对镉胁迫水稻具有解毒作用。HD228具有应用于镉污染水稻田治理的潜力。