Bioleaching of Gold from Silicate Ore by Macrococcus caseolyticus and Acinetobacter calcoaceticus: Effect of Medium, Amino Acids and Growth Supernatant

Abstract

The aims of this work were to study the gold leaching by the isolated bacteria from silicate ore. Three strains were isolated and identified as Macrococcus caseolyticus, Acinetobacter calcoaceticus, and Bacillus sp. MBEA40. However, only M. caseolyticus and A. calcoaceticus were capable of gold bioleaching. In order to examine only the effect of microorganisms involved in the gold bioleaching process, minimal medium and ethanol mineral salt medium without amino acids were used for culturing M. caseolyticus and A. calcoaceticus, respectively. The result showed that the growth supernatant (in the absence of microorganisms) of both strains might be more suitable to leaching gold from ore than leaching by microorganisms (in the presence of microorganisms) directly. This might be due to the fact that there is no interference of gold absorption and metal toxicity in microorganisms in the long-term operation. The result also confirmed that amino acids/peptides/proteins produced by microorganisms might be involved in gold bioleaching, as shown in the high-performance liquid chromatography (HPLC) results. The Fourier transform infrared spectroscopy (FTIR) study also found that amine groups and carboxylic groups played important roles in gold bioleaching by M. caseolyticus and A. calcoaceticus. In addition, the bioleaching process had significantly higher gold leaching than mixed pure amino acids due to the growth supernatant containing mixed amino acids/peptides/proteins and other compounds. Therefore, the growth supernatant of M. caseolyticus and A. calcoaceticus can be applied in gold bioleaching under neutral pH conditions, which is considered to be a safe, not corrosive, and environmentally friendly leaching process. This study is also needed further study in order to increase the percentage of gold bioleaching and decrease times.

Genome mining to unravel potential metabolic pathways linked to gallium bioleaching ability of bacterial mine isolates

“…Previous studies have already pointed out that amino acids/peptides/proteins produced by heterotrophic bacteria were involved in Ga leaching from GaAs and GaN ( Maneesuwannarat et al, 2016a , b ). More recently, Kudpeng et al (2021) reported that amino acids/peptides/proteins produced by Macrococcus caseolyticus and Acinetobacter calcoaceticus were capable of gold bioleaching from silicate ore. The Ga leaching ability of these molecules is related to the presence of charges in their structure, which varies with different pHs due to the pK values of the carboxylic and amino groups.…”

Genome mining to unravel potential metabolic pathways linked to gallium bioleaching ability of bacterial mine isolates

“…Previous studies have already pointed out that amino acids/peptides/proteins produced by heterotrophic bacteria were involved in Ga leaching from GaAs and GaN ( Maneesuwannarat et al, 2016a , b ). More recently, Kudpeng et al (2021) reported that amino acids/peptides/proteins produced by Macrococcus caseolyticus and Acinetobacter calcoaceticus were capable of gold bioleaching from silicate ore. The Ga leaching ability of these molecules is related to the presence of charges in their structure, which varies with different pHs due to the pK values of the carboxylic and amino groups.…”

Optimization Role of Potassium Carbonate in the Leaching of Guizhou’s Carlin-Type Gold Ore System with Potassium Chlorate

“…However, it is hindered by issues such as instability of polysulfides, generation of toxic and odorous gases (H 2 S and NH 3 ), deterioration of the production environment, increased consumption of leaching agents, and higher industrial production costs. , Microbial leaching has advantages, such as the ability to process complex polymetallic minerals, low production costs, environmental friendliness, and relatively simple equipment. However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. , …”

“…However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. 18,19 Chloride leaching for gold is increasingly valued for its minimal environmental pollution, low cost, fast leaching rates, high leaching efficiency, and wide applicability. This method, which originated in 1848, was initially the primary method for gold production but was later replaced by cyanide leaching due to cost and safety concerns.…”

“…However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. 18 , 19 …”

Recovery of Copper and Gold from Waste Printed Circuit Boards Using Monosodium Glutamate Supplemented with Hydrogen Peroxide

“…Table 1 shows the studies that have been involved in the extraction of metals. The authors classified the amino acids used in the leaching process into three main groups according to the amino acid sources: (1) pure amino acids [8][9][10][11][12][13], (2) microbial amino acids [14][15][16], and (3) monosodium glutamate (MSG) [17,18]. a Room temperature.…”

Genome mining to unravel potential metabolic pathways linked to gallium bioleaching ability of bacterial mine isolates

“…Previous studies have already pointed out that amino acids/peptides/proteins produced by heterotrophic bacteria were involved in Ga leaching from GaAs and GaN ( Maneesuwannarat et al, 2016a , b ). More recently, Kudpeng et al (2021) reported that amino acids/peptides/proteins produced by Macrococcus caseolyticus and Acinetobacter calcoaceticus were capable of gold bioleaching from silicate ore. The Ga leaching ability of these molecules is related to the presence of charges in their structure, which varies with different pHs due to the pK values of the carboxylic and amino groups.…”

Optimization Role of Potassium Carbonate in the Leaching of Guizhou’s Carlin-Type Gold Ore System with Potassium Chlorate

“…However, it is hindered by issues such as instability of polysulfides, generation of toxic and odorous gases (H 2 S and NH 3 ), deterioration of the production environment, increased consumption of leaching agents, and higher industrial production costs. , Microbial leaching has advantages, such as the ability to process complex polymetallic minerals, low production costs, environmental friendliness, and relatively simple equipment. However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. , …”

“…However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. 18,19 Chloride leaching for gold is increasingly valued for its minimal environmental pollution, low cost, fast leaching rates, high leaching efficiency, and wide applicability. This method, which originated in 1848, was initially the primary method for gold production but was later replaced by cyanide leaching due to cost and safety concerns.…”

“…However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. 18 , 19 …”

Recovery of Copper and Gold from Waste Printed Circuit Boards Using Monosodium Glutamate Supplemented with Hydrogen Peroxide

“…Table 1 shows the studies that have been involved in the extraction of metals. The authors classified the amino acids used in the leaching process into three main groups according to the amino acid sources: (1) pure amino acids [8][9][10][11][12][13], (2) microbial amino acids [14][15][16], and (3) monosodium glutamate (MSG) [17,18]. a Room temperature.…”

Genome mining to unravel potential metabolic pathways linked to gallium bioleaching ability of bacterial mine isolates

“…Previous studies have already pointed out that amino acids/peptides/proteins produced by heterotrophic bacteria were involved in Ga leaching from GaAs and GaN ( Maneesuwannarat et al, 2016a , b ). More recently, Kudpeng et al (2021) reported that amino acids/peptides/proteins produced by Macrococcus caseolyticus and Acinetobacter calcoaceticus were capable of gold bioleaching from silicate ore. The Ga leaching ability of these molecules is related to the presence of charges in their structure, which varies with different pHs due to the pK values of the carboxylic and amino groups.…”

Optimization Role of Potassium Carbonate in the Leaching of Guizhou’s Carlin-Type Gold Ore System with Potassium Chlorate

“…However, it is hindered by issues such as instability of polysulfides, generation of toxic and odorous gases (H 2 S and NH 3 ), deterioration of the production environment, increased consumption of leaching agents, and higher industrial production costs. , Microbial leaching has advantages, such as the ability to process complex polymetallic minerals, low production costs, environmental friendliness, and relatively simple equipment. However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. , …”

“…However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. 18,19 Chloride leaching for gold is increasingly valued for its minimal environmental pollution, low cost, fast leaching rates, high leaching efficiency, and wide applicability. This method, which originated in 1848, was initially the primary method for gold production but was later replaced by cyanide leaching due to cost and safety concerns.…”

“…However, it suffers from slow gold leaching rates and long leaching times, typically requiring 15 to 20 days, making it challenging to apply on an industrial scale. 18 , 19 …”

Recovery of Copper and Gold from Waste Printed Circuit Boards Using Monosodium Glutamate Supplemented with Hydrogen Peroxide

“…Table 1 shows the studies that have been involved in the extraction of metals. The authors classified the amino acids used in the leaching process into three main groups according to the amino acid sources: (1) pure amino acids [8][9][10][11][12][13], (2) microbial amino acids [14][15][16], and (3) monosodium glutamate (MSG) [17,18]. a Room temperature.…”