Effects of pH shock on Hg(II) complexation by exopolymers from acidithiobacillus ferrooxidans

Wenjuan Song, Chunnuan Deng, Xiangliang Pan (Lead / Corresponding author), Daoyong Zhang, Fahad A. Al-Misned, M. Golam Mortuza, Geoffrey Michael Gadd

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Acidithiobacillus ferrooxidans is a commonly used bacterial species for leaching gold ores to recover gold. The pH of A. ferrooxidans bioleachates drastically changes from around 2.0 during bioleaching to about pH 8.0 as the cells are discharged together with the mine tailings containing high levels of Hg. It is not known how such a large pH shock would affect the properties of bacterial extracellular polymeric substances (EPS) and the transport of Hg in the mine tailings. In this study, the biochemical composition, molecular distribution, fluorescence properties and Hg(II) complexation by EPS of A. ferrooxidans cultured at pH 2 and 8 were investigated. It was found that pH shock significantly altered the composition of EPS. A. ferrooxidans yielded more EPS under acid conditions than basic conditions. The acidic EPS contained more macromolecular proteins but less polysaccharide in comparison with the basic EPS. Phosphodiester functional groups in phospholipids and polysaccharides were found in the acidic EPS but not in the basic EPS. One tryptophan protein-like peak and one aromatic protein-like peak were identified in fluorescence spectra of the acidic EPS. Two aromatic protein-like peaks were identified from the fluorescence spectra of the basic EPS. The tryptophan protein-like substances in the acidic EPS interacted with Hg(II) and formed relatively stable complexes but with weak binding ability whereas the fluorescent aromatic protein-like substances in the acidic EPS did not bind Hg(II). However the aromatic protein-like substances in the basic EPS had a strong binding ability for Hg(II). The significant differences in composition and Hg complexation ability between EPS from acidic and basic environments indicate that a large pH shock during leaching of gold may exert a considerable impact on the behavior and fate of Hg in the mining areas.

Original languageEnglish
Pages (from-to)325-331
Number of pages7
JournalGeomicrobiology Journal
Volume33
Issue number3-4
DOIs
Publication statusPublished - 15 Mar 2016

Fingerprint

Acidithiobacillus
exopolymer
Complexation
complexation
Shock
protein
Gold
Proteins
fluorescence
gold
Fluorescence
Tailings
polysaccharide
Tryptophan
tailings
Leaching
Polysaccharides
Chemical analysis
leaching
Bioleaching

Keywords

  • Acidithiobacillus ferrooxidans
  • bioleaching
  • complexation
  • extracellular polymeric substances
  • fluorescence quenching
  • mercury

Cite this

Song, Wenjuan ; Deng, Chunnuan ; Pan, Xiangliang ; Zhang, Daoyong ; Al-Misned, Fahad A. ; Mortuza, M. Golam ; Gadd, Geoffrey Michael. / Effects of pH shock on Hg(II) complexation by exopolymers from acidithiobacillus ferrooxidans. In: Geomicrobiology Journal. 2016 ; Vol. 33, No. 3-4. pp. 325-331.
@article{0e6e74ad5cdf42eba057d0edbd3e418e,
title = "Effects of pH shock on Hg(II) complexation by exopolymers from acidithiobacillus ferrooxidans",
abstract = "Acidithiobacillus ferrooxidans is a commonly used bacterial species for leaching gold ores to recover gold. The pH of A. ferrooxidans bioleachates drastically changes from around 2.0 during bioleaching to about pH 8.0 as the cells are discharged together with the mine tailings containing high levels of Hg. It is not known how such a large pH shock would affect the properties of bacterial extracellular polymeric substances (EPS) and the transport of Hg in the mine tailings. In this study, the biochemical composition, molecular distribution, fluorescence properties and Hg(II) complexation by EPS of A. ferrooxidans cultured at pH 2 and 8 were investigated. It was found that pH shock significantly altered the composition of EPS. A. ferrooxidans yielded more EPS under acid conditions than basic conditions. The acidic EPS contained more macromolecular proteins but less polysaccharide in comparison with the basic EPS. Phosphodiester functional groups in phospholipids and polysaccharides were found in the acidic EPS but not in the basic EPS. One tryptophan protein-like peak and one aromatic protein-like peak were identified in fluorescence spectra of the acidic EPS. Two aromatic protein-like peaks were identified from the fluorescence spectra of the basic EPS. The tryptophan protein-like substances in the acidic EPS interacted with Hg(II) and formed relatively stable complexes but with weak binding ability whereas the fluorescent aromatic protein-like substances in the acidic EPS did not bind Hg(II). However the aromatic protein-like substances in the basic EPS had a strong binding ability for Hg(II). The significant differences in composition and Hg complexation ability between EPS from acidic and basic environments indicate that a large pH shock during leaching of gold may exert a considerable impact on the behavior and fate of Hg in the mining areas.",
keywords = "Acidithiobacillus ferrooxidans, bioleaching, complexation, extracellular polymeric substances, fluorescence quenching, mercury",
author = "Wenjuan Song and Chunnuan Deng and Xiangliang Pan and Daoyong Zhang and Al-Misned, {Fahad A.} and Mortuza, {M. Golam} and Gadd, {Geoffrey Michael}",
year = "2016",
month = "3",
day = "15",
doi = "10.1080/01490451.2015.1054007",
language = "English",
volume = "33",
pages = "325--331",
journal = "Geomicrobiology Journal",
issn = "0149-0451",
publisher = "Taylor & Francis",
number = "3-4",

}

Effects of pH shock on Hg(II) complexation by exopolymers from acidithiobacillus ferrooxidans. / Song, Wenjuan; Deng, Chunnuan; Pan, Xiangliang (Lead / Corresponding author); Zhang, Daoyong; Al-Misned, Fahad A.; Mortuza, M. Golam; Gadd, Geoffrey Michael.

In: Geomicrobiology Journal, Vol. 33, No. 3-4, 15.03.2016, p. 325-331.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effects of pH shock on Hg(II) complexation by exopolymers from acidithiobacillus ferrooxidans

AU - Song, Wenjuan

AU - Deng, Chunnuan

AU - Pan, Xiangliang

AU - Zhang, Daoyong

AU - Al-Misned, Fahad A.

AU - Mortuza, M. Golam

AU - Gadd, Geoffrey Michael

PY - 2016/3/15

Y1 - 2016/3/15

N2 - Acidithiobacillus ferrooxidans is a commonly used bacterial species for leaching gold ores to recover gold. The pH of A. ferrooxidans bioleachates drastically changes from around 2.0 during bioleaching to about pH 8.0 as the cells are discharged together with the mine tailings containing high levels of Hg. It is not known how such a large pH shock would affect the properties of bacterial extracellular polymeric substances (EPS) and the transport of Hg in the mine tailings. In this study, the biochemical composition, molecular distribution, fluorescence properties and Hg(II) complexation by EPS of A. ferrooxidans cultured at pH 2 and 8 were investigated. It was found that pH shock significantly altered the composition of EPS. A. ferrooxidans yielded more EPS under acid conditions than basic conditions. The acidic EPS contained more macromolecular proteins but less polysaccharide in comparison with the basic EPS. Phosphodiester functional groups in phospholipids and polysaccharides were found in the acidic EPS but not in the basic EPS. One tryptophan protein-like peak and one aromatic protein-like peak were identified in fluorescence spectra of the acidic EPS. Two aromatic protein-like peaks were identified from the fluorescence spectra of the basic EPS. The tryptophan protein-like substances in the acidic EPS interacted with Hg(II) and formed relatively stable complexes but with weak binding ability whereas the fluorescent aromatic protein-like substances in the acidic EPS did not bind Hg(II). However the aromatic protein-like substances in the basic EPS had a strong binding ability for Hg(II). The significant differences in composition and Hg complexation ability between EPS from acidic and basic environments indicate that a large pH shock during leaching of gold may exert a considerable impact on the behavior and fate of Hg in the mining areas.

AB - Acidithiobacillus ferrooxidans is a commonly used bacterial species for leaching gold ores to recover gold. The pH of A. ferrooxidans bioleachates drastically changes from around 2.0 during bioleaching to about pH 8.0 as the cells are discharged together with the mine tailings containing high levels of Hg. It is not known how such a large pH shock would affect the properties of bacterial extracellular polymeric substances (EPS) and the transport of Hg in the mine tailings. In this study, the biochemical composition, molecular distribution, fluorescence properties and Hg(II) complexation by EPS of A. ferrooxidans cultured at pH 2 and 8 were investigated. It was found that pH shock significantly altered the composition of EPS. A. ferrooxidans yielded more EPS under acid conditions than basic conditions. The acidic EPS contained more macromolecular proteins but less polysaccharide in comparison with the basic EPS. Phosphodiester functional groups in phospholipids and polysaccharides were found in the acidic EPS but not in the basic EPS. One tryptophan protein-like peak and one aromatic protein-like peak were identified in fluorescence spectra of the acidic EPS. Two aromatic protein-like peaks were identified from the fluorescence spectra of the basic EPS. The tryptophan protein-like substances in the acidic EPS interacted with Hg(II) and formed relatively stable complexes but with weak binding ability whereas the fluorescent aromatic protein-like substances in the acidic EPS did not bind Hg(II). However the aromatic protein-like substances in the basic EPS had a strong binding ability for Hg(II). The significant differences in composition and Hg complexation ability between EPS from acidic and basic environments indicate that a large pH shock during leaching of gold may exert a considerable impact on the behavior and fate of Hg in the mining areas.

KW - Acidithiobacillus ferrooxidans

KW - bioleaching

KW - complexation

KW - extracellular polymeric substances

KW - fluorescence quenching

KW - mercury

UR - http://www.scopus.com/inward/record.url?scp=84959224040&partnerID=8YFLogxK

U2 - 10.1080/01490451.2015.1054007

DO - 10.1080/01490451.2015.1054007

M3 - Article

VL - 33

SP - 325

EP - 331

JO - Geomicrobiology Journal

JF - Geomicrobiology Journal

SN - 0149-0451

IS - 3-4

ER -