Insights into the role of extracellular DNA in heavy metal adsorption

Tangjian Peng; Wanqing Liao; Guohua Gu; Guanzhou Qiu; Xueling Wu; Fei Yang; Weimin Zeng

doi:10.1016/j.scitotenv.2021.152067

Insights into the role of extracellular DNA in heavy metal adsorption

Sci Total Environ. 2022 Feb 20:808:152067. doi: 10.1016/j.scitotenv.2021.152067. Epub 2021 Dec 1.

Authors

Tangjian Peng¹, Wanqing Liao², Guohua Gu², Guanzhou Qiu², Xueling Wu², Fei Yang³, Weimin Zeng⁴

Affiliations

¹ Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang 421001, China; School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
² School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
³ Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang 421001, China; Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha 410078, China.
⁴ School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; CSIRO Process Science and Engineering, Clayton, Victoria 3168, Australia. Electronic address: zengweimin1024@126.com.

PMID: 34863749
DOI: 10.1016/j.scitotenv.2021.152067

Abstract

Extracellular polymeric substances (EPS) participate in heavy metal adsorption in the aquatic environments. Extracellular DNA (eDNA) is an essential component of EPS, but its involvement in metal binding remains ambiguous. Herein, the role of eDNA in Cd(II) and Ni(II) adsorption was described using a combination of semi-quantitative and qualitative approaches. EPS were extracted from Burkholderia sp. MBR-1 and eDNA accounted for 6.9% of the total mass of EPS. The eDNA in the extracted EPS was digested using the DNase II to prepare an eDNA-free EPS sample. Potentiometric titration unveiled that the number of total binding sites of the eDNA-free EPS was 19% lower than the untreated EPS. The Cd(II) and Ni(II) adsorption capacity of the eDNA-free EPS was lower than the untreated EPS at the pH range of 4-7. At pH 7, the results of batch adsorption experiments showed that removing eDNA from EPS resulted in declines of 12.6% and 15.7% in the adsorption capacities for Cd(II) and Ni(II), respectively. Furthermore, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy unraveled that the phosphoryl groups and purines of eDNA are responsible for Cd(II) and Ni(II) complexation. The results demonstrated that eDNA plays an essential role in heavy metal adsorption.

Keywords: Adsorption; EPS; Functional groups; Heavy metal; eDNA.

MeSH terms

Adsorption
DNA
Extracellular Polymeric Substance Matrix
Metals, Heavy*
Spectroscopy, Fourier Transform Infrared

Substances

Metals, Heavy
DNA