title: Isolation and characterization of a novel Acidithiobacillus ferrivorans strain from the Chilean Altiplano: attachment and biofilm formation on pyrite at low temperature.
abstract: Microorganisms are used to aid the extraction of valuable metals from low-grade sulfide ores in mines worldwide, but relatively little is known about this process in cold environments. This study comprises a preliminary analysis of the bacterial diversity of the polyextremophilic acid River Aroma located in the Chilean Altiplano, and revealed that Betaproteobacteria was the most dominant bacterial group (Gallionella-like and Thiobacillus-like). Taxa characteristic of leaching environments, such Acidithiobacillus and Leptospirillum, were detected at low abundances. Also, bacteria not associated with extremely acidic, metal-rich environments were found. After enrichment in iron- and sulfur-oxidizing media, we isolated and identified a novel psychrotolerant Acidithiobacillus ferrivorans strain ACH. This strain can grow using ferrous iron, sulfur, thiosulfate, tetrathionate and pyrite, as energy sources. Optimal growth was observed in the presence of pyrite, where cultures reached a cell number of 6.5 · 10(7) cells mL(-1). Planktonic cells grown with pyrite showed the presence of extracellular polymeric substances (10 °C and 28 °C), and a high density of cells attached to pyrite grains were observed at 10 °C by electron microscopy. The attachment of cells to pyrite coupons and the presence of capsular polysaccharides were visualized by using epifluorescence microscopy, through nucleic acid and lectin staining with Syto(®)9 and TRITC-Con A, respectively. Interestingly, we observed high cell adhesion including the formation of microcolonies within 21 days of incubation at 4 °C, which was correlated with a clear induction of capsular polysaccharides production. Our data suggests that attachment to pyrite is not temperature-dependent in At. ferrivorans ACH. The results of this study highlight the potential of this novel psychrotolerant strain in oxidation and attachment to minerals under low-temperature conditions.
authors.affiliation: Laboratorio de Tecnología de Membranas, Biotecnología y Medio Ambiente, Departamento de Ingeniería Química, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile; Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Centro de Bioinnovación, Facultad de Ciencias del Mar y Recursos Biológicos, Departamento de Biotecnología, Universidad de Antofagasta, Avenida Angamos 0601, Antofagasta, Chile. Electronic address: barahona.sergio.l@gmail.com.
authors.forename: Sergio
authors.initials: S
authors.lastname: Barahona
authors.affiliation: Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Centro de Bioinnovación, Facultad de Ciencias del Mar y Recursos Biológicos, Departamento de Biotecnología, Universidad de Antofagasta, Avenida Angamos 0601, Antofagasta, Chile. Electronic address: cristina.dorador@uantof.cl.
authors.forename: Cristina
authors.initials: C
authors.lastname: Dorador
authors.affiliation: Biofilm Centre, University of Dusiburg-Essen, 5, 45141 Essen, Germany. Electronic address: ruiyong.zhang@uni-due.de.
authors.forename: Ruiyong
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Laboratorio de Tecnología de Membranas, Biotecnología y Medio Ambiente, Departamento de Ingeniería Química, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile; Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Centro de Bioinnovación, Facultad de Ciencias del Mar y Recursos Biológicos, Departamento de Biotecnología, Universidad de Antofagasta, Avenida Angamos 0601, Antofagasta, Chile. Electronic address: pabloaguilar.e@gmail.com.
authors.forename: Pablo
authors.initials: P
authors.lastname: Aguilar
authors.affiliation: Biofilm Centre, University of Dusiburg-Essen, 5, 45141 Essen, Germany. Electronic address: wolfgang.sand@uni-due.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Sand
authors.affiliation: Biofilm Centre, University of Dusiburg-Essen, 5, 45141 Essen, Germany. Electronic address: mario.vera@uni-due.de.
authors.forename: Mario
authors.initials: M
authors.lastname: Vera
authors.affiliation: Laboratorio de Tecnología de Membranas, Biotecnología y Medio Ambiente, Departamento de Ingeniería Química, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile. Electronic address: fremonse@ucn.cl.
authors.forename: Francisco
authors.initials: F
authors.lastname: Remonsellez
mesh_terms: D042763:Acidithiobacillus / Q000302:isolation & purification* / Q000378:metabolism* / Q000502:physiology*; D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D002677:Chile; D016000:Cluster Analysis; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D007287:Inorganic Chemicals / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013440:Sulfides / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007287:Inorganic Chemicals; D012336:RNA, Ribosomal, 16S; D013440:Sulfides; C011342:pyrite; D007501:Iron
keywords: 16S rRNA gene; Acidithiobacillus ferrivorans; Attachment; Biofilm; Polyextremophilic environment; Psychrotolerant