title: Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans.
abstract: Massive pyrite (FeS₂) electrodes were potentiostatically modified by means of variable oxidation pulse to induce formation of diverse surface sulfur species (S(n)²⁻, S⁰). The evolution of reactivity of the resulting surfaces considers transition from passive (e.g., Fe(1-x )S₂) to active sulfur species (e.g., Fe(1-x )S(2-y ), S⁰). Selected modified pyrite surfaces were incubated with cells of sulfur-oxidizing Acidithiobacillus thiooxidans for 24 h in a specific culture medium (pH 2). Abiotic control experiments were also performed to compare chemical and biological oxidation. After incubation, the attached cells density and their exopolysaccharides were analyzed by confocal laser scanning microscopy (CLMS) and atomic force microscopy (AFM) on bio-oxidized surfaces; additionally, S(n)²⁻/S⁰ speciation was carried out on bio-oxidized and abiotic pyrite surfaces using Raman spectroscopy. Our results indicate an important correlation between the evolution of S(n)²⁻/S⁰ surface species ratio and biofilm formation. Hence, pyrite surfaces with mainly passive-sulfur species were less colonized by A. thiooxidans as compared to surfaces with active sulfur species. These results provide knowledge that may contribute to establishing interfacial conditions that enhance or delay metal sulfide (MS) dissolution, as a function of the biofilm formed by sulfur-oxidizing bacteria.
authors: Departamento de Química, Área de Electroquímica, Universidad Autónoma Metropolitana-Iztapalapa, Av. Rafael Atlixco 186, Col. Vicentina, 09340 México, DF, Mexico. lcrh75@hotmail.com
authors: René H
authors: RH
authors: Lara
authors: J Viridiana
authors: JV
authors: García-Meza
authors: Roel
authors: R
authors: Cruz
authors: Donato
authors: D
authors: Valdez-Pérez
authors: Ignacio
authors: I
authors: González
mesh_terms: D013856:Acidithiobacillus thiooxidans / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D003470:Culture Media / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D013059:Spectrum Analysis, Raman; D013440:Sulfides / Q000378:metabolism*
chemical_list: D003470:Culture Media; D013440:Sulfides; C011342:pyrite; D007501:Iron