TY - JOUR
T1 - Evolution of biofilms during the colonization process of pyrite by Acidithiobacillus thiooxidans
AU - González, Dulce M.
AU - Lara, René H.
AU - Alvarado, Keila N.
AU - Valdez-Pérez, Donato
AU - Navarro-Contreras, Hugo R.
AU - Cruz, Roel
AU - García-Meza, Jessica Viridiana
N1 - Funding Information:
Acknowledgments Financial support for this work comes from the Mexican Council of Science and Technology (CONACyT; project no. 05-49321). The authors thank Dr. Amauri Pozos and Dr. Jaime Ruiz-García for access to the CLSM (Basics Sciences Laboratory) and the AFM (Colloids and Interfaces Laboratory) equipment at UASLP, respectively. The authors also thank Erasmo Mata-Martinez for mineral section preparation, Francisco Galindo-Murillo for MPE preparation. René Lara also thanks CONACyT for his postdoctoral fellowship.
PY - 2012/1
Y1 - 2012/1
N2 - We have applied epifluorescence principles, atomic force microscopy, and Raman studies to the analysis of the colonization process of pyrite (FeS 2) by sulfuroxidizing bacteria Acidithiobacillus thiooxidans after 1, 15, 24, and 72 h. For the stages examined, we present results comprising the evolution of biofilms, speciation of S n 2- /S 0 species, adhesion forces of attached cells, production and secretion of extracellular polymeric substances (EPS), and its biochemical composition. After 1 h, highly dispersed attached cells in the surface of the mineral were observed. The results suggest initial non-covalent, weak interactions (e.g., van der Waal's, hydrophobic interactions), mediating an irreversible binding mechanism to electrooxidized massive pyrite electrode (eMPE), wherein the initial production of EPS by individual cells is determinant. The mineral surface reached its maximum cell cover between 15 to 24 h. Longer biooxidation times resulted in the progressive biofilm reduction on the mineral surface. Quantification of attached cell adhesion forces indicated a strong initial mechanism (8.4 nN), whereas subsequent stages of mineral colonization indicated stability of biofilms and of the adhesion force to an average of 4.2 nN. A variable EPS (polysaccharides, lipids, and proteins) secretion at all stages was found; thus, different architectural conformation of the biofilms was observed during 120 h. The main EPS produced were lipopolysaccharides which may increase the hydrophobicity of A. thiooxidans biofilms. The highest amount of lipopolysaccharides occurred between 15-72 h. In contrast with abiotic surfaces, the progressive depletion of S n 2- /S 0 was observed on biotic eMPE surfaces, indicating consumption of surface sulfur species. All observations indicated a dynamic biooxidation mechanism of pyrite by A. thiooxidans, where the biofilms stability and composition seems to occur independently from surface sulfur species depletion.
AB - We have applied epifluorescence principles, atomic force microscopy, and Raman studies to the analysis of the colonization process of pyrite (FeS 2) by sulfuroxidizing bacteria Acidithiobacillus thiooxidans after 1, 15, 24, and 72 h. For the stages examined, we present results comprising the evolution of biofilms, speciation of S n 2- /S 0 species, adhesion forces of attached cells, production and secretion of extracellular polymeric substances (EPS), and its biochemical composition. After 1 h, highly dispersed attached cells in the surface of the mineral were observed. The results suggest initial non-covalent, weak interactions (e.g., van der Waal's, hydrophobic interactions), mediating an irreversible binding mechanism to electrooxidized massive pyrite electrode (eMPE), wherein the initial production of EPS by individual cells is determinant. The mineral surface reached its maximum cell cover between 15 to 24 h. Longer biooxidation times resulted in the progressive biofilm reduction on the mineral surface. Quantification of attached cell adhesion forces indicated a strong initial mechanism (8.4 nN), whereas subsequent stages of mineral colonization indicated stability of biofilms and of the adhesion force to an average of 4.2 nN. A variable EPS (polysaccharides, lipids, and proteins) secretion at all stages was found; thus, different architectural conformation of the biofilms was observed during 120 h. The main EPS produced were lipopolysaccharides which may increase the hydrophobicity of A. thiooxidans biofilms. The highest amount of lipopolysaccharides occurred between 15-72 h. In contrast with abiotic surfaces, the progressive depletion of S n 2- /S 0 was observed on biotic eMPE surfaces, indicating consumption of surface sulfur species. All observations indicated a dynamic biooxidation mechanism of pyrite by A. thiooxidans, where the biofilms stability and composition seems to occur independently from surface sulfur species depletion.
KW - Acidithiobacillus thiooxidans
KW - Biofilms evolution
KW - Electrooxidation
KW - Interfacial analysis
KW - Proteins quantification
KW - Pyrite
UR - http://www.scopus.com/inward/record.url?scp=84856291064&partnerID=8YFLogxK
U2 - 10.1007/s00253-011-3465-2
DO - 10.1007/s00253-011-3465-2
M3 - Artículo
SN - 0175-7598
VL - 93
SP - 763
EP - 775
JO - Applied Microbiology and Biotechnology
JF - Applied Microbiology and Biotechnology
IS - 2
ER -