Cadmium Selenide Formation Influences the Production and Characteristics of Extracellular Polymeric Substances of Anaero
- PDF / 1,361,979 Bytes
- 16 Pages / 439.37 x 666.142 pts Page_size
- 22 Downloads / 206 Views
Cadmium Selenide Formation Influences the Production and Characteristics of Extracellular Polymeric Substances of Anaerobic Granular Sludge Joyabrata Mal 1,2,3 & Yarlagadda V. Nancharaiah 4,5 & Isabelle Bourven 2 & Stéphane Simon 2 & Eric D. van Hullebusch 6 & Gilles Guibaud 2 & Piet N. L. Lens 1,7 Received: 23 July 2020 / Accepted: 9 November 2020/ # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
Feeding cadmium (II) and selenium (IV) simultaneously to anaerobic granular sludge with the aim of synthesizing cadmium selenide (CdSe) nanoparticles induces compositional changes in the extracellular polymeric substances (EPS) matrix of this sludge. A methanogenic anaerobic granular sludge was repeatedly exposed to Cd(II) (10–50 mg L−1) and selenite (79 mg L−1) for 300 days at pH 7.3 and 30 °C in a fed-batch feeding regime for enrichment of Se-reducing bacteria and synthesis of CdSe nanoparticles. EPS fingerprints of the granular sludge, obtained by size exclusion chromatography coupled to a fluorescence detector, showed a significant increase in the intensity of protein-like substances with > 100 kDa apparent molecular weight (aMW) upon repeated exposure to Cd(II) and Se(VI). This was accompanied by a prominent decrease in protein-like substances of aMW < 10 kDa. The fingerprint of the humic-like substances showed emergence of a new peak with aMW of 13 to 300 kDa in the EPS extracted from the Cd/Se fed granular sludge. Experiments on metal(loid)–EPS interactions showed that the CdSe nanoparticles interact mainly with loosely bound EPS (LB-EPS). This study showed that the formation of Se(0) and CdSe nanoparticles occurs in the LB-EPS fraction of the granular sludge and repeated exposure to Cd and Se induces compositional changes in the EPS matrix. Keywords Extracellular polymeric substances (EPS) . Size exclusion chromatography (SEC) fingerprint . Molecule size distribution . Anaerobicgranular sludge . Selenium . Cadmiumselenide
* Joyabrata Mal [email protected]; [email protected] Extended author information available on the last page of the article
Applied Biochemistry and Biotechnology
Introduction Extracellular polymeric substances (EPS) are a complex mixture of high molecular weight macromolecules comprising mainly of proteins, carbohydrates, and humic-like substances [1–3]. EPS play a significant role in microorganism-metal interactions, i.e., sorption, bioreduction, and biomineralization, thus determining the biogeochemical cycling of metal ions as well as the transformation and immobilization of metals in natural environments [4–6]. EPS make direct contact and interact with the metals and nanoparticles before the metals enter the cells and thus play a vital role in protecting the microbial cells [7–11]. An intimate association of EPS with biogenic nanoparticles (NPs), e.g., those of selenium, tellurium, silver, and palladium NPs, has also been reported [12–15]. The EPS may mediate reduction of metal(loid)s or provide nucleation sites for biogenic NPs formation [5, 16, 1
Data Loading...
