Experimental and modeling studies of competitive Pb (II) and Cd (II) bioaccumulation by Aspergillus niger

• Published in: Applied microbiology and biotechnology Vol. 105; no. 16-17; pp. 6477 - 6488
• Main Authors: Qiu, Jingjing, Song, Xinwei, Li, Sensen, Zhu, Bihe, Chen, Yanting, Zhang, Lin, Li, Zhen
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2021; Springer Nature B.V
• Subjects: Aspergillus niger; Bioaccumulation; Biological activity; Biomedical and Life Sciences; Bioremediation; Biotechnology; Cadmium; Cations; Citric acid; Coordination compounds; Environmental Biotechnology; Environmental cleanup; Fungi; Heavy metals; Immobilization; Lead; Life Sciences; Microbial activity; Microbial Genetics and Genomics; Microbiology; Microorganisms; Modelling; Pyruvic acid; Remediation; Soil investigations; Soil water; Toxicity; Tricarboxylic acid cycle; Water pollution; Competition; Fungus; Cd; Pb; GWB modeling; Biosorption; Toxicity
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-021-11497-3

Co-existence of toxic metals causes complex toxicity to microorganisms during bioremediation in water and soil. This study investigated the immobilization of Pb 2+ and Cd 2+ by fungus Aspergillus niger , which has been widely applied to environmental remediation. Five treatments were set, i.e., CK (no toxic metals), Pb 2+ only, Cd 2+ only, Pb 2+ /Cd 2+ = 1:1(molar ratio), and Pb 2+ /Cd 2+ = 2:1. Cadmium induced strong toxicity to the fungus, and maintained the high toxicity during incubation. However, as Pb/Cd ratio increased from 0 to 2, the removal rates of Cd 2+ by A. niger were raised from 30 to 50%. The elevated activities of pyruvate dehydrogenase (PDH) and citrate synthetase (CS) enzymes confirmed that Pb addition could stimulate the growth of A. niger . For instance, citric acid concentrations and CS activities were 463.22 mg/L and 78.37 nmol/min/g, respectively, during 3-day incubation as Pb/Cd = 1. However, these two values were as low as ~ 50 with addition of only Cd. It was hence assumed that appropriate co-existence of Pb 2+ enhanced microbial activity by promoting TCA cycle of the fungus. Moreover, the SEM analysis and geochemical modeling demonstrated that Pb 2+ cations were more easily adsorbed and mineralized on A. niger with respect to Cd 2+ . Therefore, instead of intensifying metal toxicity, the addition of appropriate Pb actually weakened Cd toxicity to the fungus. This study sheds a bright future on application of A. niger to the remediation of polluted water with co-existence of Pb and Cd. Key points: • Cd 2+ significantly inhibited P consumption, suggesting its high toxicity to A. niger . • Pb 2+ stimulated the growth of A. niger by promoting TCA cycle in the cells. • Cd 2+ removal by A. niger were improved with co-existence of Pb 2+ .