一株黑曲霉的筛选及其对河道底泥重金属的生物淋滤去除

Isolation of Aspergillus niger SY1 and its role in bioleaching of heavy metals from contaminated river sediments

生物淋滤,特别是异养生物淋滤,是最有前景的污染介质重金属绿色消减方式,但在污染底泥的处理中还没有得到广泛应用。本研究采集沈阳细河疏浚底泥,并从中筛选得到高效淋滤丝状真菌SY1,经形态学及ITS r DNA基因序列分析鉴定为黑曲霉,命名为Aspergillus niger SY1,测定了其生长特性,采用摇瓶培养法去除污染底泥中重金属的效果。结果表明:细河底泥受到重金属Cd污染最为严重,含量为33.3 mg·kg^(-1),且以生物可利用态为主;SY1最适合的温度为25～35℃,最适合初始pH值为6.0～7.0;该菌株生长代谢过程中产生葡萄糖酸和草酸,最高分别达14.7和6.4 g·L^(-1)。在最优条件下(底泥浓度为20g·L^(-1)、糖浓度为100 g·L^(-1)、孢子浓度为2×10~7个·m L^(-1)),经过SY1 8天的淋滤,底泥中Cd、Pb、Cu和Zn淋出率分别为93.5%、11.4%、62.3%和68.2%。因此,SY1是比较有潜力的重金属底泥淋滤菌株,可用于重金属污染疏浚底泥的淋滤修复。

Bioleaching,especially heterotrophic bioleaching,is a promising way to reduce heavy metals in contaminated medium.However,such method has not been widely used in the treatment of contaminated sediments.In this study,the contaminated sediments were collected from the dredging of the Xihe River(Shenyang).A heterotrophic fungus named SY1 was isolated from the sediments and identified as Apergillus niger through morphological and molecular methods.Its growth and acid production characteristics,as well as its role in leaching heavy metals from contaminated soil were investigated using shake flask culture.The results showed that the sediments were seriously contaminated by Cd,with a concentration of 33.3 mg·kg-1and mainly in the bioavailable state.A.niger SY1 well adapted to a wide range of temperature from 25 to 30℃and optimal initial pH value of 6.0-7.0.A large amount of glucose acid and oxalic acid(as high as14.7 and 6.4 g·L-1respectively)was generated in the bioleaching process.Under the optimal conditions(sediment concentration of 20 g·L-1,sugar concentration of 100 g·L-1,and spore concentration of 2×107ind·m L-1),93.5%Cd,11.4%Pb,62.3%Cu and 68.2%Zn were leached out after incubating SY1 for eight days.Therefore,A.niger strain SY1 is a cost-effective and efficient bioleacher of heavy metals,which could be used in the remediation of heavy metal contaminated dredged sediments.