D. Fortin | University of Ottawa | Université d'Ottawa (original) (raw)

Papers by D. Fortin

Research paper thumbnail of Characterization of Fe-S minerals influenced by buried ancient woods in the intertidal zone, East China Sea

Chinese Science Bulletin, 2009

An ancient wood layer dated at about 5600 cal. a BP by AMS 14 C dating was discovered in the inte... more An ancient wood layer dated at about 5600 cal. a BP by AMS 14 C dating was discovered in the intertidal zone, East China Sea. Samples affected by ancient woods, including fresh coast bedrock, weathering bedrock, seepage water from coast, seepage water from ancient wood layer, intertidal seawater, fresh water, beach mud, ancient wood barks and ancient peat, were collected for geochemical analysis. The beach mud and the bacteriogenic iron oxides (BIOS) in coastal seepage water were analyzed by mineralogical and high-resolution transmission electron microscopy (HRTEM)-selected area electron diffraction (SAED) analysis. Inorganic sulfur compositions and δ 34 S of the ancient peat and the beach mud were determined. The results showed that Fe, Mn, S (SO 4 2−) were enriched in the intertidal area at different levels, very likely caused by fermentation of ancient woods. The presence of abundant ironoxidizing bacteria (FeOB) and sulfate-reducing bacteria (SRB) in this intertidal zone was confirmed by HRTEM-SAED observation, and these bacteria were involved in Fe-S cycle to induce extracellular biomineralization. The negative δ 34 S V-CDT (−2.9‰) likely indicated the biogenic origin of iron-sulfide minerals in the beach mud at high sulfate reduction rate (SRR). These findings are helpful for understanding the biogeochemical Fe-S cycle and biomineralization process at high organic matter deposition rate and high SRR in the intertidal zone, estuary, or near shoreline. Intertidal zone, ancient wood layer, Fe-S minerals, iron-oxidizing bacteria (FeOB), sulfate-reducing bacteria (SRB), East China Sea OCEANOLOGY

Research paper thumbnail of Nickel sulfide, iron-nickel sulfide and iron sulfide precipitation by a newly isolated Desulfotomaculum species and its relation to nickel resistance

FEMS Microbiology Ecology, 1994

A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Che... more A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Chengdu (P.R.C.) was resistant to 360 (6.1 mM), 450 (7.7 mM), and 550 ppm (9.4 mM) Ni(II) in the presence of 0, 100 (1.8 mM), and 200 ppm (3.6 raM) Fe(II), respectively. When cultured in the presence of Ni (II) with or without Fe, DF-1 produced a dark-brown, soluble product. Only small amounts of Ni and or Fe were precipitated at the cell surface when cells were subjected to 100 ppm concentrations of the metals. However, in the presence of Fe (II) only, large amounts of FeS (70% of the Fe) were precipitated at the bacterial cell surface and extracellularly. The increase of Ni in the growth medium was inversely related to the concentration of Fe precipitated as a sulfide. This coincided with the formation of dark-brown, soluble Ni-proteins, consisting of a range of polypeptides from approx. 70-120 kDa, which inhibited NiS formation and promoted Fe-complexation. These autolysis-inducible proteins and cell wall autolysis by-products bound Ni, and are thought to confer Ni-resistance in DF-1. Harsh treatments, such as acidification of culture supernatants from Ni-grown DF-1, destabilized the Ni-organic complexes, and resulted in the precipitation of an amorphous Ni-rich material.

Research paper thumbnail of The evolution of geomicrobiology: perspectives from the mineral?bacteria interface

Geobiology, 2007

This issue of Geobiology provides a glimpse into the state of geomicrobiology with research prese... more This issue of Geobiology provides a glimpse into the state of geomicrobiology with research presented spanning from molecular-scale cellular metal interactions to field studies of elemental cycling. The broad link between all of these papers

Research paper thumbnail of Nickel sulfide, iron-nickel sulfide and iron sulfide precipitation by a newly isolated Desulfotomaculum species and its relation to nickel resistance

Fems Microbiology Ecology, 1994

A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Che... more A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Chengdu (P.R.C.) was resistant to 360 (6.1 mM), 450 (7.7 mM), and 550 ppm (9.4 mM) Ni(II) in the presence of 0, 100 (1.8 mM), and 200 ppm (3.6 mM) Fe(II), respectively. When cultured in the presence of Ni (II) with or without Fe, DF-1 produced a dark-brown, soluble product. Only small amounts of Ni and or Fe were precipitated at the cell surface when cells were subjected to 100 ppm concentrations of the metals. However, in the presence of Fe(II) only, large amounts of FeS (70% of the Fe) were precipitated at the bacterial cell surface and extracellularly. The increase of Ni in the growth medium was inversely related to the concentration of Fe precipitated as a sulfide. This coincided with the formation of dark-brown, soluble Ni-proteins, consisting of a range of polypeptides from approx. 70–120 kDa, which inhibited NiS formation and promoted Fe-complexation. These autolysis-inducible protei...

Research paper thumbnail of Role of Thiobacillus and sulfate-reducing bacteria in iron biocycling in oxic and acidic mine tailings

FEMS Microbiology Ecology, 2000

The tailings of the abandoned Kam Kotia mine (Cu-Zn ore) located near Timmins, Ontario, Canada, w... more The tailings of the abandoned Kam Kotia mine (Cu-Zn ore) located near Timmins, Ontario, Canada, were studied to understand the role of bacteria in Fe cycling. Tailings samples taken along a 70 cm deep profile were oxidized and acidic (pH 2-4). The release of large concentrations of dissolved Fe and SOi-in the surface pore waters coincided with the presence of large populations of Thiobacillus, an acidophilic iron-oxidizing bacterium. The chemical and microbial oxidation by 7'hiobaciZlm of Fe-sulfides was extensive in the Kam Kotia tailings and corresponded to a near depletion of the pyrite content of the tailings around the same depth. Concurrently, de novo biomineralization occurred within the tailings as indicated by the enrichment of Fe-oxide minerals close to the tailings bacteria. Bacteria, such as T&bacillus, provided binding sites for dissolved metal species and served as nucleation surfaces for the development of Fe-rich minerals under acidic conditions. Sulfate-reducing bacteria (SRB) were also recovered in the tailings, in the lower portion of the profile where slightly oxidizing and acidic (pH 3-4) conditions prevailed. SRB possibly survived in microenvironments having more reduced and alkaline conditions because they did not tolerate oxidizing and acidic conditions when grown in the presence of different electron donors in the laboratory. However, SRB isolated from the tailings were able to grow with low concentrations of organic carbon, formate and acetate detected at concentrations lower than 1 mM in the pore waters appeared to be the main electron donors for SRB. These organic acids likely originated as small metabolic excretion products of living biomass or from the degradation of dead biomass (e.g. Fe-oxidizing bacteria) present in the tailings. SRB locally affected the cycling of Fe in the tailings by promoting the formation of small amounts of Fe-monosulfides. However, the cycling of Fe in the lower portion of the tailings was mainly driven by the precipitation of melanterite (FeS0,.7H,O) following the oxidation of pyrite and the release of large amounts of dissolved Fe and SO:- .

Research paper thumbnail of Sorption of rare earth elements by Bacillus subtilis

Adsorption of rare earth elements (REE) onto the cell walls of Bacillus subtilis (a gram-positive... more Adsorption of rare earth elements (REE) onto the cell walls of Bacillus subtilis (a gram-positive bacterium) and Escherichia coli (a gram-negative bacterium) was studied between pH 2.5 and 4.5 and at various bacterial concentrations. The distribution coefficients of REE between the bacterial cell surface and water showed a pattern with a prominent enrichment of heavy REE (HREE), including a maximum around Sm and Eu. There was also an enrichment around Pr accompanied by a decline for Nd, which was attributed to the tetrad effect. The occurrence of M-type tetrad effect suggests that REE form inner sphere complexes during their adsorption onto bacteria.

Research paper thumbnail of Characterization of Fe-S minerals influenced by buried ancient woods in the intertidal zone, East China Sea

Chinese Science Bulletin, 2009

An ancient wood layer dated at about 5600 cal. a BP by AMS 14 C dating was discovered in the inte... more An ancient wood layer dated at about 5600 cal. a BP by AMS 14 C dating was discovered in the intertidal zone, East China Sea. Samples affected by ancient woods, including fresh coast bedrock, weathering bedrock, seepage water from coast, seepage water from ancient wood layer, intertidal seawater, fresh water, beach mud, ancient wood barks and ancient peat, were collected for geochemical analysis. The beach mud and the bacteriogenic iron oxides (BIOS) in coastal seepage water were analyzed by mineralogical and high-resolution transmission electron microscopy (HRTEM)-selected area electron diffraction (SAED) analysis. Inorganic sulfur compositions and δ 34 S of the ancient peat and the beach mud were determined. The results showed that Fe, Mn, S (SO 4 2−) were enriched in the intertidal area at different levels, very likely caused by fermentation of ancient woods. The presence of abundant ironoxidizing bacteria (FeOB) and sulfate-reducing bacteria (SRB) in this intertidal zone was confirmed by HRTEM-SAED observation, and these bacteria were involved in Fe-S cycle to induce extracellular biomineralization. The negative δ 34 S V-CDT (−2.9‰) likely indicated the biogenic origin of iron-sulfide minerals in the beach mud at high sulfate reduction rate (SRR). These findings are helpful for understanding the biogeochemical Fe-S cycle and biomineralization process at high organic matter deposition rate and high SRR in the intertidal zone, estuary, or near shoreline. Intertidal zone, ancient wood layer, Fe-S minerals, iron-oxidizing bacteria (FeOB), sulfate-reducing bacteria (SRB), East China Sea OCEANOLOGY

Research paper thumbnail of Nickel sulfide, iron-nickel sulfide and iron sulfide precipitation by a newly isolated Desulfotomaculum species and its relation to nickel resistance

FEMS Microbiology Ecology, 1994

A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Che... more A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Chengdu (P.R.C.) was resistant to 360 (6.1 mM), 450 (7.7 mM), and 550 ppm (9.4 mM) Ni(II) in the presence of 0, 100 (1.8 mM), and 200 ppm (3.6 raM) Fe(II), respectively. When cultured in the presence of Ni (II) with or without Fe, DF-1 produced a dark-brown, soluble product. Only small amounts of Ni and or Fe were precipitated at the cell surface when cells were subjected to 100 ppm concentrations of the metals. However, in the presence of Fe (II) only, large amounts of FeS (70% of the Fe) were precipitated at the bacterial cell surface and extracellularly. The increase of Ni in the growth medium was inversely related to the concentration of Fe precipitated as a sulfide. This coincided with the formation of dark-brown, soluble Ni-proteins, consisting of a range of polypeptides from approx. 70-120 kDa, which inhibited NiS formation and promoted Fe-complexation. These autolysis-inducible proteins and cell wall autolysis by-products bound Ni, and are thought to confer Ni-resistance in DF-1. Harsh treatments, such as acidification of culture supernatants from Ni-grown DF-1, destabilized the Ni-organic complexes, and resulted in the precipitation of an amorphous Ni-rich material.

Research paper thumbnail of The evolution of geomicrobiology: perspectives from the mineral?bacteria interface

Geobiology, 2007

This issue of Geobiology provides a glimpse into the state of geomicrobiology with research prese... more This issue of Geobiology provides a glimpse into the state of geomicrobiology with research presented spanning from molecular-scale cellular metal interactions to field studies of elemental cycling. The broad link between all of these papers

Research paper thumbnail of Nickel sulfide, iron-nickel sulfide and iron sulfide precipitation by a newly isolated Desulfotomaculum species and its relation to nickel resistance

Fems Microbiology Ecology, 1994

A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Che... more A Desulfotomaculum sp. (DF-1) isolated from a sulfate reduction bioremediation pilot plant in Chengdu (P.R.C.) was resistant to 360 (6.1 mM), 450 (7.7 mM), and 550 ppm (9.4 mM) Ni(II) in the presence of 0, 100 (1.8 mM), and 200 ppm (3.6 mM) Fe(II), respectively. When cultured in the presence of Ni (II) with or without Fe, DF-1 produced a dark-brown, soluble product. Only small amounts of Ni and or Fe were precipitated at the cell surface when cells were subjected to 100 ppm concentrations of the metals. However, in the presence of Fe(II) only, large amounts of FeS (70% of the Fe) were precipitated at the bacterial cell surface and extracellularly. The increase of Ni in the growth medium was inversely related to the concentration of Fe precipitated as a sulfide. This coincided with the formation of dark-brown, soluble Ni-proteins, consisting of a range of polypeptides from approx. 70–120 kDa, which inhibited NiS formation and promoted Fe-complexation. These autolysis-inducible protei...

Research paper thumbnail of Role of Thiobacillus and sulfate-reducing bacteria in iron biocycling in oxic and acidic mine tailings

FEMS Microbiology Ecology, 2000

The tailings of the abandoned Kam Kotia mine (Cu-Zn ore) located near Timmins, Ontario, Canada, w... more The tailings of the abandoned Kam Kotia mine (Cu-Zn ore) located near Timmins, Ontario, Canada, were studied to understand the role of bacteria in Fe cycling. Tailings samples taken along a 70 cm deep profile were oxidized and acidic (pH 2-4). The release of large concentrations of dissolved Fe and SOi-in the surface pore waters coincided with the presence of large populations of Thiobacillus, an acidophilic iron-oxidizing bacterium. The chemical and microbial oxidation by 7'hiobaciZlm of Fe-sulfides was extensive in the Kam Kotia tailings and corresponded to a near depletion of the pyrite content of the tailings around the same depth. Concurrently, de novo biomineralization occurred within the tailings as indicated by the enrichment of Fe-oxide minerals close to the tailings bacteria. Bacteria, such as T&bacillus, provided binding sites for dissolved metal species and served as nucleation surfaces for the development of Fe-rich minerals under acidic conditions. Sulfate-reducing bacteria (SRB) were also recovered in the tailings, in the lower portion of the profile where slightly oxidizing and acidic (pH 3-4) conditions prevailed. SRB possibly survived in microenvironments having more reduced and alkaline conditions because they did not tolerate oxidizing and acidic conditions when grown in the presence of different electron donors in the laboratory. However, SRB isolated from the tailings were able to grow with low concentrations of organic carbon, formate and acetate detected at concentrations lower than 1 mM in the pore waters appeared to be the main electron donors for SRB. These organic acids likely originated as small metabolic excretion products of living biomass or from the degradation of dead biomass (e.g. Fe-oxidizing bacteria) present in the tailings. SRB locally affected the cycling of Fe in the tailings by promoting the formation of small amounts of Fe-monosulfides. However, the cycling of Fe in the lower portion of the tailings was mainly driven by the precipitation of melanterite (FeS0,.7H,O) following the oxidation of pyrite and the release of large amounts of dissolved Fe and SO:- .

Research paper thumbnail of Sorption of rare earth elements by Bacillus subtilis

Adsorption of rare earth elements (REE) onto the cell walls of Bacillus subtilis (a gram-positive... more Adsorption of rare earth elements (REE) onto the cell walls of Bacillus subtilis (a gram-positive bacterium) and Escherichia coli (a gram-negative bacterium) was studied between pH 2.5 and 4.5 and at various bacterial concentrations. The distribution coefficients of REE between the bacterial cell surface and water showed a pattern with a prominent enrichment of heavy REE (HREE), including a maximum around Sm and Eu. There was also an enrichment around Pr accompanied by a decline for Nd, which was attributed to the tetrad effect. The occurrence of M-type tetrad effect suggests that REE form inner sphere complexes during their adsorption onto bacteria.