ISSN:
1662-8985
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Extracellular polymeric substances (EPS) of Acidithiobacillus ferrooxidans and otherleaching microorganisms mediate the attachment of cells to pyrite and other minerals. They alsoplay a pivotal role in indirect leaching of base and precious metals via the contact mechanism. Theaim of this study is to get more insight on the influence of the growth substrates iron(II) ions, pyrite,chalcopyrite and elemental sulfur on EPS formation, attachment and biofilm formation. Thesynthesis of EPS by cells of A. ferrooxidans strain A2 is strongely influenced by the growthsubstrate or attachment substratum of the cells. Cells grown with soluble iron(II) ions generallygenerate less EPS than cells grown with solid pyrite, chalcopyrite or elemental sulfur. Planktoniccells grown in the presence of solid substrate produce two to four times more EPS than iron(II) iongrown cells. With sessile cells, this factor is further increased to 50 to 240 depending on the specificsubstrate. The EPS of all the differently grown planktonic and sessile cells of A. ferrooxidans strainA2 contained neutral sugars, fatty acids, uronic acids, proteins and metal ions. The composition ofthese compounds varied with the growth substrate and type (planktonic or sessile). The attachmentbehavior of cells of A. ferrooxidans strain A2 also differed with the substrate of the pre-culture.Cells grown on iron(II) ions, pyrite or chalcopyrite attached rapidly to pyrite and chalcopyrite,while attachment to elemental sulfur was poor. On the contrary, sulfur grown cells attached well toelemental sulfur but weakly to pyrite and chalcopyrite. Attachment of EPS-free cells to allsubstrates was also diminished. Cells of A. ferrooxidans strain A2 cover mineral surfaces with adense biofilm after a few days of cultivation, as visualized by fluorescence microscopy and AFM.Large amounts of EPS are formed, which eventually cover the cells and the mineral surface. Evenafter a few weeks of cultivation the biofilm remained monolayered on all substrates
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.385.pdf
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