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Degradation of cyano-complexes by an Escherichia coli strain
132
Abstracts
BIOSOLUBILIZATION /BIOSORPTION Biosolubilization of Heavy Metals from Biosolids J.L.R. Reis and D.M.L. Da Motta Maques CPG em Recursos Hidricos e Saneamento Ambiental, UFRGS, Porto Aiegre, RS, Brazil
The disposal of biosolids produced by domestic and industrial wastewater treatment has been a major problem. From an economic viewpoint, disposal in arable soil has frequently been shown to be viable. However, the greater part of this biosolid cannot be used as manure and/or soil conditioner because of its high heavy metal content, which could damage human health and the environment. The application of biological activity in the extraction of metals from biosolids is a relatively new technique. The bacteria involved in this process, the genus Thiobacillus, catalyse the extraction of metals. They are very versatile organisms with an extraordinary adaptability to high acid and metal ion concentrations. Biosolubilisation is mainly of interest because of its relatively low cost. Thus the bacterial recovery of heavy metals from biosolids seems to be a perfectly viable alternative technology for reducing environmental problems. Apart from this, the method allows the determination of metal solubilising potential from biosolids using sulphur-oxidizing bacteria and different pulp densities.
strains exposed to 100 and 300 ppm of Cu, the maximum accumulation occurred at the beginning of the stationary phase. Although there was no significant difference in the growth rate, the strains varied in their ability to uptake Cu. Techniques of light microscopy, environmental scanning electron microscopy and atomic force microscopy were used to image bacterial cells grown in the presence of 300 ppm of cu2+. Characterization and mapping of elements associated with bacterial biomass, using Energy Dispersive Xray Analysis and Proton Induced X-ray Spectroscopy, revealed the abundance of Cu, P and Ca ions. X-ray photoelectron spectroscopy demonstrated that Cu deposited outside bacterial cells was present as Cu’+. This preliminary investigation indicates that for the two strains of P. syringae biosorption/biomineralization is a major mechanism of Cu resistance and that complex copper compounds are formed as a result of interactions between bacterial cells and Cu ions.
Accumulation and Recovery of Metals by Aspergilfus mger in Cyanide-containing Solutions from Gold Mining N.C.M. Games, E.M.S. Camargos, J.C.T. Dias, M.M. Figueira and V.R. Lmardi
Use of Organic Materials for tbe Removal of Heavy Metals
Departamento de Microbiologia, UFMG, Belo Horizonte, Brazil
N.M.E. Rossoni, J.A.F. Da R. Pereira and E.M. De Santana
In order to evaluate the metal-accumulating potential of fungal strains isolated and from a metal-containing solution, the strains were grown in a solution containing metals and high cyanide concentration and enriched with 0.5% peptone and 1% glucose at pH 8.0. Aspergillus niger was able to accumulate 57% of the gold, 100% of the silver and 5545% of the copper present in the solution at the beginning of the log phase (72 h of incubation). During the period of metal accumulation the cyanide was completely removed from the medium. The metals accumulated by the cells after 86 h of incubation were easily recovered after a treatment with 0.1 M thiourea for 2 h. Our results demonstrate that A. niger can have potential use in the removal and/or recovery of metals from cyanide-containing solutions from gold extraction plant. (Grants: CAPES, FAPEMIC, PrPq.)
Universidade Federal de Bahia, Brazil
Heavy metals represent a greater danger to terrestrial species. Apart from being non-biodegradable, they become concentrated within the food chain and are extremely harmful to life. The increase in these heavy metals within the environment reflects growing industrialisation in certain regions. With the aim of reducing the disposal of these compounds in the environment, removal methods employing live, dead or decomposing organic matter were studied. These methods have the advantage of generating more readily treated wastes than conventional physico-chemical methods. One such method was tested on wastes from oil production. The method chosen uses living organic material and has the advantage of removing heavy metals in relatively low concentrations and at the same time degrading the majority of organic materials present in the waste.
Biosorption of Copper by Pseudomonas syringae spp. - Preliminary Investigation LB. Beech”, S.L.S. Woo“ and G.G. Geese$ “University of Portsmouth, UK and bCenter for Biofilm Engineering, Montana State University, USA
The aim of this study was to determine the ability of two copper resistant strains of Pseudomonas syringae to remove Cu2+ ions, added as copper sulfate, from liquid growth media and to elucidate the mechanism of Cu biosorption. Atomic absorption analysis showed that for both bacterial
Degradation of Cyano-Complexes by an Escherichia coli Strain G.C.C. Nauter, M.M. Figueira and V.R. Linardi Departamento de Microbiologia, UFMG, Belo Horizonte, Brazil
Cyanide compounds are commonly used in various industries, such as chemical intermediates production, synthesis of methacrylates, dyes, synthetic fibers and agricultural products. Gold mining and electroplating industries are responsible for large amounts of cyanide released into the environment. Due to high toxicity, cyanide-containing waste water must be treated before release in order to meet the regulatory require-
Abstracts
ments. The present study reports the capacity of an E. co/i strain, isolated from gold extraction circuit liquid, to grow in different cyanide complexes as the sole source of nitrogen. The bacteria were able to grow in the presence of 5.0 mg CN-/I as copper cyanide and 100 mg CN-/I as zinc and ferric cyanides. The biosorption of metals liberated from cyano-complexes are being investigated. (Grants: CNPq, FAPEMIG, PrPq/ UFMG.)
rubra strain grew in presence of 0.57 mM silver cyanide. Some
of these strains could be promising for use in bioprocesses for the treatment of cyano-metal-containing effluents. (Grants: CNPq, CAPES, PrPq/UFMG.)
Bacterial Leaching Applied to a Sulfide Ore of Copper from Salobo Mine, Carajas, PA, Brazil F.J. Gomes’ and J. Frenayb
Bioleaching, the Improvementof Bioleaching Organisms and the Molecular Biology of Thiobucihs ferrooxiduns D.E. Rawhgs Department of Microbiology, University of Cape Town, Rondebosch, South Africa
Bioleaching has been successfully applied on a commercial scale to the recovery of several metals, especially copper, uranium and gold. Processes for the extraction of copper and uranium have existed for many years, but it was only during the 1980s that the biooxidation of gold-bearing arsenopyrite ores was reduced to commercial practice. A key to the commercialization of this process was the development of a highly-active, rapidly-growing, arsenic-resistant bacterial consortium. The empirical technique of mutation and selection in a continuous-flow system was used to improve the rate and ability of the bacteria to decompose arsenopyrite ore. This approach resulted in a dramatic initial enhancement in growth rate. However, a plateau in improvement of performance has been reached. Further advances will require a more direct approach based on an understanding of the underlying physiological mechanisms and an application of the tools of molecular biology. A review of bioleaching, the commercialization of the gold ore treatment process and some of the progress in our knowledge of the molecular biology of the bacteria involved will be presented.
Yeast Occurrence in a Cold Mining Plant and Screening for Degradation of Cyano-Metals C.T. Dias, N.C.M. Gomes, C.A. Rosa and V.R. Linardi Departamento de Microbiologia, UFMG, Belo Horizonte, Brazil
Gold extractive procedures that utilize cyanidation frequently generate toxic effluents that must be treated before discharge in the environment. We are studying yeast occurrence and distribution in a gold mining plant, and intend to isolate strains with ability to degrade cyano-metals. Sixty-three yeast strains were isolated from five different points of the gold mining effluent. Candida famata. Rhodotorula glutinis e Geotrichum sp. were the most frequently isolated yeast species. Eight yeast strains grew on Yeast Carbon Base with 0.45 mM ferric cyanide as sole nitrogen source. Eight strains grew in presence of 0.38 mM copper cyanide, and one Rhodotorula
“Fundapao Gorceix, Ouro Preto, MG, Brazil and bUniversitP de Liege, Department Metallurgic de Non Ferreux, Liege, Belgium
The present work investigates the aspects of bioleaching applied to a sample of a copper ore from Salobo mine, belonging to Companhia Vale do Rio Dote (Brazil). The effect of process parameters (pH, pulp density, inoculum volume and others) on the rate of copper solubilization is analyzed through tests in shake flasks (200 rpm at 30°C) and different percolation columns (diameter = 80, h = 250 and diameter = 200 mm, h = 1200 mm). A discussion of these results based on a suggested mechanism is presented. The sulfide copper mineral bioleaching has shown at least 72% copper solubilization. On the other hand the tests in absence of microorganisms have shown a solubilization rate around 50% but with high consumption of sulfuric acid. The different rates of metal extraction shown here can be explained taking into consideration the physical and physical-chemical properties of the samples. Finally, the implications concerning bioleaching industrial circuit applications are presented.
Solubilization of Zinc and Nickel from Different Silicated Minerals by Bacteria and Fungi F.J. Gomesa, J.L.M. Rangelb, N.G. Marquesb, R.X. Vieirab, M.J.M. Tr6piab, I.M. Castrob and R.L. BrandHo “Funda@o Gorceix, Ouro Preto, M.G., and bLaboratdrio de Bioquimica e Fisiologia de Microrganismos, ICEB II, UFOP, Ouro Preto, MG, Brazil
We have studied the utilization of different microorganisms to improve the solubilization of two different metals, zinc and nickel, from silicated minerals. In conventional processes the yield of this solubilization can be affected by the mineralogical properties. In this context, biotechnological processes could be used as an alternative way to try and solve the problem. The experiments were done in shake flasks (200 rpm), at 30°C and particle size
Abstracts
BIOSOLUBILIZATION /BIOSORPTION Biosolubilization of Heavy Metals from Biosolids J.L.R. Reis and D.M.L. Da Motta Maques CPG em Recursos Hidricos e Saneamento Ambiental, UFRGS, Porto Aiegre, RS, Brazil
The disposal of biosolids produced by domestic and industrial wastewater treatment has been a major problem. From an economic viewpoint, disposal in arable soil has frequently been shown to be viable. However, the greater part of this biosolid cannot be used as manure and/or soil conditioner because of its high heavy metal content, which could damage human health and the environment. The application of biological activity in the extraction of metals from biosolids is a relatively new technique. The bacteria involved in this process, the genus Thiobacillus, catalyse the extraction of metals. They are very versatile organisms with an extraordinary adaptability to high acid and metal ion concentrations. Biosolubilisation is mainly of interest because of its relatively low cost. Thus the bacterial recovery of heavy metals from biosolids seems to be a perfectly viable alternative technology for reducing environmental problems. Apart from this, the method allows the determination of metal solubilising potential from biosolids using sulphur-oxidizing bacteria and different pulp densities.
strains exposed to 100 and 300 ppm of Cu, the maximum accumulation occurred at the beginning of the stationary phase. Although there was no significant difference in the growth rate, the strains varied in their ability to uptake Cu. Techniques of light microscopy, environmental scanning electron microscopy and atomic force microscopy were used to image bacterial cells grown in the presence of 300 ppm of cu2+. Characterization and mapping of elements associated with bacterial biomass, using Energy Dispersive Xray Analysis and Proton Induced X-ray Spectroscopy, revealed the abundance of Cu, P and Ca ions. X-ray photoelectron spectroscopy demonstrated that Cu deposited outside bacterial cells was present as Cu’+. This preliminary investigation indicates that for the two strains of P. syringae biosorption/biomineralization is a major mechanism of Cu resistance and that complex copper compounds are formed as a result of interactions between bacterial cells and Cu ions.
Accumulation and Recovery of Metals by Aspergilfus mger in Cyanide-containing Solutions from Gold Mining N.C.M. Games, E.M.S. Camargos, J.C.T. Dias, M.M. Figueira and V.R. Lmardi
Use of Organic Materials for tbe Removal of Heavy Metals
Departamento de Microbiologia, UFMG, Belo Horizonte, Brazil
N.M.E. Rossoni, J.A.F. Da R. Pereira and E.M. De Santana
In order to evaluate the metal-accumulating potential of fungal strains isolated and from a metal-containing solution, the strains were grown in a solution containing metals and high cyanide concentration and enriched with 0.5% peptone and 1% glucose at pH 8.0. Aspergillus niger was able to accumulate 57% of the gold, 100% of the silver and 5545% of the copper present in the solution at the beginning of the log phase (72 h of incubation). During the period of metal accumulation the cyanide was completely removed from the medium. The metals accumulated by the cells after 86 h of incubation were easily recovered after a treatment with 0.1 M thiourea for 2 h. Our results demonstrate that A. niger can have potential use in the removal and/or recovery of metals from cyanide-containing solutions from gold extraction plant. (Grants: CAPES, FAPEMIC, PrPq.)
Universidade Federal de Bahia, Brazil
Heavy metals represent a greater danger to terrestrial species. Apart from being non-biodegradable, they become concentrated within the food chain and are extremely harmful to life. The increase in these heavy metals within the environment reflects growing industrialisation in certain regions. With the aim of reducing the disposal of these compounds in the environment, removal methods employing live, dead or decomposing organic matter were studied. These methods have the advantage of generating more readily treated wastes than conventional physico-chemical methods. One such method was tested on wastes from oil production. The method chosen uses living organic material and has the advantage of removing heavy metals in relatively low concentrations and at the same time degrading the majority of organic materials present in the waste.
Biosorption of Copper by Pseudomonas syringae spp. - Preliminary Investigation LB. Beech”, S.L.S. Woo“ and G.G. Geese$ “University of Portsmouth, UK and bCenter for Biofilm Engineering, Montana State University, USA
The aim of this study was to determine the ability of two copper resistant strains of Pseudomonas syringae to remove Cu2+ ions, added as copper sulfate, from liquid growth media and to elucidate the mechanism of Cu biosorption. Atomic absorption analysis showed that for both bacterial
Degradation of Cyano-Complexes by an Escherichia coli Strain G.C.C. Nauter, M.M. Figueira and V.R. Linardi Departamento de Microbiologia, UFMG, Belo Horizonte, Brazil
Cyanide compounds are commonly used in various industries, such as chemical intermediates production, synthesis of methacrylates, dyes, synthetic fibers and agricultural products. Gold mining and electroplating industries are responsible for large amounts of cyanide released into the environment. Due to high toxicity, cyanide-containing waste water must be treated before release in order to meet the regulatory require-
Abstracts
ments. The present study reports the capacity of an E. co/i strain, isolated from gold extraction circuit liquid, to grow in different cyanide complexes as the sole source of nitrogen. The bacteria were able to grow in the presence of 5.0 mg CN-/I as copper cyanide and 100 mg CN-/I as zinc and ferric cyanides. The biosorption of metals liberated from cyano-complexes are being investigated. (Grants: CNPq, FAPEMIG, PrPq/ UFMG.)
rubra strain grew in presence of 0.57 mM silver cyanide. Some
of these strains could be promising for use in bioprocesses for the treatment of cyano-metal-containing effluents. (Grants: CNPq, CAPES, PrPq/UFMG.)
Bacterial Leaching Applied to a Sulfide Ore of Copper from Salobo Mine, Carajas, PA, Brazil F.J. Gomes’ and J. Frenayb
Bioleaching, the Improvementof Bioleaching Organisms and the Molecular Biology of Thiobucihs ferrooxiduns D.E. Rawhgs Department of Microbiology, University of Cape Town, Rondebosch, South Africa
Bioleaching has been successfully applied on a commercial scale to the recovery of several metals, especially copper, uranium and gold. Processes for the extraction of copper and uranium have existed for many years, but it was only during the 1980s that the biooxidation of gold-bearing arsenopyrite ores was reduced to commercial practice. A key to the commercialization of this process was the development of a highly-active, rapidly-growing, arsenic-resistant bacterial consortium. The empirical technique of mutation and selection in a continuous-flow system was used to improve the rate and ability of the bacteria to decompose arsenopyrite ore. This approach resulted in a dramatic initial enhancement in growth rate. However, a plateau in improvement of performance has been reached. Further advances will require a more direct approach based on an understanding of the underlying physiological mechanisms and an application of the tools of molecular biology. A review of bioleaching, the commercialization of the gold ore treatment process and some of the progress in our knowledge of the molecular biology of the bacteria involved will be presented.
Yeast Occurrence in a Cold Mining Plant and Screening for Degradation of Cyano-Metals C.T. Dias, N.C.M. Gomes, C.A. Rosa and V.R. Linardi Departamento de Microbiologia, UFMG, Belo Horizonte, Brazil
Gold extractive procedures that utilize cyanidation frequently generate toxic effluents that must be treated before discharge in the environment. We are studying yeast occurrence and distribution in a gold mining plant, and intend to isolate strains with ability to degrade cyano-metals. Sixty-three yeast strains were isolated from five different points of the gold mining effluent. Candida famata. Rhodotorula glutinis e Geotrichum sp. were the most frequently isolated yeast species. Eight yeast strains grew on Yeast Carbon Base with 0.45 mM ferric cyanide as sole nitrogen source. Eight strains grew in presence of 0.38 mM copper cyanide, and one Rhodotorula
“Fundapao Gorceix, Ouro Preto, MG, Brazil and bUniversitP de Liege, Department Metallurgic de Non Ferreux, Liege, Belgium
The present work investigates the aspects of bioleaching applied to a sample of a copper ore from Salobo mine, belonging to Companhia Vale do Rio Dote (Brazil). The effect of process parameters (pH, pulp density, inoculum volume and others) on the rate of copper solubilization is analyzed through tests in shake flasks (200 rpm at 30°C) and different percolation columns (diameter = 80, h = 250 and diameter = 200 mm, h = 1200 mm). A discussion of these results based on a suggested mechanism is presented. The sulfide copper mineral bioleaching has shown at least 72% copper solubilization. On the other hand the tests in absence of microorganisms have shown a solubilization rate around 50% but with high consumption of sulfuric acid. The different rates of metal extraction shown here can be explained taking into consideration the physical and physical-chemical properties of the samples. Finally, the implications concerning bioleaching industrial circuit applications are presented.
Solubilization of Zinc and Nickel from Different Silicated Minerals by Bacteria and Fungi F.J. Gomesa, J.L.M. Rangelb, N.G. Marquesb, R.X. Vieirab, M.J.M. Tr6piab, I.M. Castrob and R.L. BrandHo “Funda@o Gorceix, Ouro Preto, M.G., and bLaboratdrio de Bioquimica e Fisiologia de Microrganismos, ICEB II, UFOP, Ouro Preto, MG, Brazil
We have studied the utilization of different microorganisms to improve the solubilization of two different metals, zinc and nickel, from silicated minerals. In conventional processes the yield of this solubilization can be affected by the mineralogical properties. In this context, biotechnological processes could be used as an alternative way to try and solve the problem. The experiments were done in shake flasks (200 rpm), at 30°C and particle size