Enhancement of Biofilm Formation on Pyrite by Sulfobacillus thermosulfidooxidans

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Abstract:At the industrial scale, bioleaching of metal sulfides includes two main technologies, tank leaching and heap leaching. Fluctuations in temperature caused by the exothermic reactions in a heap have a pronounced effect on the growth of microbes and composition of mixed microbial populations. Currently, little is known on the influence of pre-colonized mesophiles or moderate thermophiles on the attachment and bioleaching efficiency by thermophiles. The objective of this study was to investigate the interspecies interactions of the moderate thermophile Sulfobacillus thermosulfidooxidans DSM 9293 T and the thermophile Acidianus sp. DSM 29099 during initial attachment to and dissolution of pyrite. Our results showed that: (1) Acidianus sp. DSM 29099 interacted with S. thermosulfidooxidans T during initial attachment in mixed cultures. In particular, cell attachment was improved in mixed cultures compared to pure cultures alone; however, no improvement of pyrite leaching in mixed cultures compared with pure cultures was observed; (2) active or inactivated cells of S. thermosulfidooxidans T on pyrite inhibited or showed no influence on the initial attachment of Acidianus sp. DSM 29099, respectively, but both promoted its leaching efficiency; (3) S. thermosulfidooxidans T exudates did not enhance the initial attachment of Acidianus sp. DSM 29099 to pyrite, but greatly facilitated its pyrite dissolution efficiency. Our study provides insights into cell-cell interactions between moderate thermophiles and thermophiles and is helpful for understanding of the microbial interactions in a heap leaching environment.

“…Figure S3). Biofilm formation by S. thermosulfidooxidans T cells on pyrite decreased after seven days of incubation [45]. The biofilm formation of Acidianus sp.…”

Section: Influence Of S Thermosulfidooxidans T Exudates On Initial Amentioning

confidence: 98%

Influence of Sulfobacillus thermosulfidooxidans on Initial Attachment and Pyrite Leaching by Thermoacidophilic Archaeon Acidianus sp. DSM 29099

Liu

Sand

et al. 2016

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“…According to the indirect "contact" mechanism the oxidation of minerals is caused by Fe (III) ions complexed in extracellular polymeric substances (EPS). Thus, adhesion and biofilm formation by iron-oxidizing bacteria is essential for an efficient biooxidation or bioleaching of sulfide minerals [16][17][18][19][20]. The EPS mediate cell attachment to minerals as well as electrochemical reactions taking place at mineral surfaces during bioleaching processes [16,19,21].…”

Section: Introductionmentioning

confidence: 99%

Adhesion to Mineral Surfaces by Cells of Leptospirillum, Acidithiobacillus and Sulfobacillus from Armenian Sulfide Ores

Vardanyan¹,

Vardanyan²,

Khachatryan³

et al. 2019

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Bioleaching of metal sulfides is an interfacial process where adhesion and subsequent biofilm formation are considered to be crucial for this process. In this study, adhesion and biofilm formation by several acidophiles (Acidithiobacillus, Leptospirillum and Sulfobacillus) isolated from different biotopes with sulfide ores in Armenia were studied. Results showed that: (1) these bacteria adhere to pyrite surfaces to various extents. A correlation between pyrite biooxidation and adhesion of S. thermosulfidooxidans 6, L. ferriphilum CC, L. ferrooxidans ZC on pyrite surfaces is shown. It is supposed that bioleaching of pyrite by S. thermosulfidooxidans 6, L. ferriphilum CC, L. ferrooxidans ZC occurs by means of indirect leaching: by ferric iron of bacterial origin; (2) cells of At. ferrooxidans 61, L. ferrooxidans ZC and St. thermosulfidooxidans 6 form a monolayer biofilm on pyrite surfaces. The coverage of pyrite surfaces varies among these species. The order of the biofilm coverage is: L. ferrooxidans ZC ≥ At. ferrooxidans 61 > St. thermosulfidooxidans 6; (3) the extracellular polymeric substances (EPS) analysis indicates that the tested strains produce EPS, if grown either on soluble ferrous iron or solid pyrite. EPS are mainly composed of proteins and carbohydrates. Cells excrete higher amounts of capsular EPS than of colloidal EPS. In addition, cells grown on pyrite produce more EPS than ones grown on ferrous iron.

“…Motility is one pivotal factor. Number of attached cells is low and no biofilms form on mineral surfaces if microorganisms are immotile [39]. Microorganisms prefer to attach to imperfections such as dislocations and cracks [11,12,40].…”

Section: Attachment Of Planktonic Cells To Chalcopyrite Powdermentioning

confidence: 99%

Comparative Analysis of Attachment to Chalcopyrite of Three Mesophilic Iron and/or Sulfur-Oxidizing Acidophiles

Yang

Zhu

et al. 2018

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Adhesion plays an important role in bacterial dissolution of metal sulfides, since the attached cells initiate the dissolution. In addition, biofilms, forming after bacterial attachment, enhance the dissolution. In this study, interactions between initial adhesion force, attachment behavior and copper recovery were comparatively analyzed for Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferrooxidans during bioleaching of chalcopyrite. The adhesion forces between bacteria and minerals were measured by atomic force microscopy (AFM). L. ferrooxidans had the largest adhesion force and attached best to chalcopyrite, while A. ferrooxidans exhibited the highest bioleaching of chalcopyrite. The results suggest that the biofilm formation, rather than the initial adhesion, is positively correlated with bioleaching efficiency.