Abstract: 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^-1 and 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 as 14.7 and 6.4 g·L^-1 respectively) 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 2×10⁷ ind·mL^-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.

Key words: species composition, dominant species, biomass, diversity, environmental factor, temporal and spatial pattern.