X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of ...X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.展开更多
The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied....The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.展开更多
Bioleaching experiments combined with X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)and scanning electron microscopy(SEM)were conducted to investigate three kinds of bornites from different regions leach...Bioleaching experiments combined with X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)and scanning electron microscopy(SEM)were conducted to investigate three kinds of bornites from different regions leached by moderately thermophilic mixed bacteria of Leptospirillum ferriphilum YSK,Acidithiobacillus caldus D1 and Sulfobacillus thermosulfidooxidans ST.The results of bioleaching experiments showed that the leaching efficiency and the redox potential were significantly increased.The copper extraction efficiencies of three kinds of bornite maintained rapid growth until around the 12th day and no longer increased after the 18th,reaching 83.7%,96.5%and 86.6%,respectively.The XRD results of the leaching residue indicated that three kinds of bornites all produced jarosite in the late stage of leaching,and the leaching residues from of Daye Museum and Yunnan Geological Museum contained a mass of elemental sulfur.XPS analysis and scanning electron microscopy experiments showed that the surface of mineral particles was jarosite and the copper in the leaching residue was almost dissolved.展开更多
In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45--65℃ （with 55℃ being the optimum temperature） was isolated from oil-contaminated soil of Karamay in...In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45--65℃ （with 55℃ being the optimum temperature） was isolated from oil-contaminated soil of Karamay in Xinjiang, China. Denaturing gradient gel electrophoresis （DGGE） showed that there were nine strains included in KO8-2, which originated from the genera of Bacillus, Geobacillus and Clostridium. They all belonged to thermophilic bacteria, and had been previously proved as degraders of at least one petroleum fraction. The crude oil degraded by KO8-2 was analyzed by infrared spectrophotometry, hydrocarbon group type analysis and gas chromatography. The results indicated that the bacterial consortium KO8-2 was able to utilize 64.33% of saturates, 27.06% of aromatics, 13.24% of resins and the oil removal efficiency reached up to 58.73% at 55 ~C when the oil concentration was 10 g/L. Detailed analysis showed that KO8-2 was able to utilize the hydrocarbon components before C19, and the n-alkanes ranging from C20--C33 were signifi- cantly degraded. The ratios of nC17/Pr and nC18/Ph were 3.12 and 3.87, respectively, before degradation, whereas after degradation the ratios reduced to 0.21 and 0.38, respectively. Compared with the control sample, the oil removal efficiency in KO8-2 composting reactor reached 50.12% after a degradation duration of 60 days.展开更多
A refractory gold concentrate with 19% arsenic was treated by a mixed moderately thermophiles in an airlift bioreactor through an adaptation protocol. The moderately thermophiles could respond well to 20%(w/v) pulp de...A refractory gold concentrate with 19% arsenic was treated by a mixed moderately thermophiles in an airlift bioreactor through an adaptation protocol. The moderately thermophiles could respond well to 20%(w/v) pulp density with less than 10% loss of productivity, and resist arsenic up to 15 g/L. There were a lot of jarosite, arsenolite and sulfur, but not scorodite and ferric arsenate in the bioleached residue. Jarosite passivation and lower sulfur-oxidizing activity of the cells due to the toxicity of the high concentrations of soluble arsenic and iron ions at low p H value should mainly response for the incomplete extraction at high pulp density. The initial bacterial community did not change in nature except for new found P aeruginosa ANSC, but sulfur-oxidizing microorganisms have been dominant microorganisms after a long time of adaptation. Pseudomonas aeruginosa originating from the gold concentrate should be closely relative to the metabolism of the organic matters contained in the refractory gold concentrate.展开更多
Cellulose is the main structural component of lignocellulosic wastes that can be converted to sugars and biofuels by cellulase.Due to wide applications of this enzyme in various industries around the world,cellulase i...Cellulose is the main structural component of lignocellulosic wastes that can be converted to sugars and biofuels by cellulase.Due to wide applications of this enzyme in various industries around the world,cellulase is considered as the third industrial enzyme.The ability of thermophilic bacteria in the production of heat-stable cellulases has made them valuable tools in biotechnology.The aim of this study was isolation and molecular identification of cellulolytic thermophile bacteria from Dig Rostam hot spring and investigating their cellulase activity.Samples were taken from water and sediments of this hot spring,and cellulolytic bacteria were enriched in media containing cellulose as the only carbon source.The bacteria were incubated at 60℃,and single colonies were then isolated on solid media.Congo red assay was used as a quick test for the qualitative screening of cellulase activity.According to these qualitative results,four colonies named CDB1,CDB2,CDB3,and CDB4 were isolated,and their growth curve and some other characteristics were determined by biochemical assays.Moreover,endoglucanase,exoglucanase,and FPase activities of the isolates were investigated quantitatively.Results indicated that CDB1 exhibited the highest endoglucanase(0.096 U/mL)and exoglucanase(0.156 U/mL)activities among other isolates.16S rDNA partial sequencing indicated that CDB1 had 99%similarity to the genus Anoxybacillus,and the other isolates showed the highest similarity to the genus Geobacillus.The cellulase gene of CDB1 isolate with the highest cellulase activity was also cloned,and its sequence is reported for the first time.Further studies on this thermophilic enzyme might be useful for industrial applications.展开更多
基金Projects(51374248,51320105006)supported by the National Natural Science Foundation of ChinaProject(NCET-13-0595)supported by the Program for New Century Excellent Talents in University,ChinaProject(2014T70692)supported by China Postdoctoral Science Foundation
文摘X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.
基金Project (41271330) supported by the National Natural Science Foundation of China
文摘The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.
基金Project(51974363)supported by the National Natural Science Foundation of China。
文摘Bioleaching experiments combined with X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)and scanning electron microscopy(SEM)were conducted to investigate three kinds of bornites from different regions leached by moderately thermophilic mixed bacteria of Leptospirillum ferriphilum YSK,Acidithiobacillus caldus D1 and Sulfobacillus thermosulfidooxidans ST.The results of bioleaching experiments showed that the leaching efficiency and the redox potential were significantly increased.The copper extraction efficiencies of three kinds of bornite maintained rapid growth until around the 12th day and no longer increased after the 18th,reaching 83.7%,96.5%and 86.6%,respectively.The XRD results of the leaching residue indicated that three kinds of bornites all produced jarosite in the late stage of leaching,and the leaching residues from of Daye Museum and Yunnan Geological Museum contained a mass of elemental sulfur.XPS analysis and scanning electron microscopy experiments showed that the surface of mineral particles was jarosite and the copper in the leaching residue was almost dissolved.
基金the support provided by the Research&Technology Development Project of China National Petroleum Corporation(No.2008D-4704-2)
文摘In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45--65℃ （with 55℃ being the optimum temperature） was isolated from oil-contaminated soil of Karamay in Xinjiang, China. Denaturing gradient gel electrophoresis （DGGE） showed that there were nine strains included in KO8-2, which originated from the genera of Bacillus, Geobacillus and Clostridium. They all belonged to thermophilic bacteria, and had been previously proved as degraders of at least one petroleum fraction. The crude oil degraded by KO8-2 was analyzed by infrared spectrophotometry, hydrocarbon group type analysis and gas chromatography. The results indicated that the bacterial consortium KO8-2 was able to utilize 64.33% of saturates, 27.06% of aromatics, 13.24% of resins and the oil removal efficiency reached up to 58.73% at 55 ~C when the oil concentration was 10 g/L. Detailed analysis showed that KO8-2 was able to utilize the hydrocarbon components before C19, and the n-alkanes ranging from C20--C33 were signifi- cantly degraded. The ratios of nC17/Pr and nC18/Ph were 3.12 and 3.87, respectively, before degradation, whereas after degradation the ratios reduced to 0.21 and 0.38, respectively. Compared with the control sample, the oil removal efficiency in KO8-2 composting reactor reached 50.12% after a degradation duration of 60 days.
基金Project(2010CB630903)supported by the National Basic Research Program of ChinaProject(31200382)supported by the Chinese Science Foundation for Distinguished Group,China
文摘A refractory gold concentrate with 19% arsenic was treated by a mixed moderately thermophiles in an airlift bioreactor through an adaptation protocol. The moderately thermophiles could respond well to 20%(w/v) pulp density with less than 10% loss of productivity, and resist arsenic up to 15 g/L. There were a lot of jarosite, arsenolite and sulfur, but not scorodite and ferric arsenate in the bioleached residue. Jarosite passivation and lower sulfur-oxidizing activity of the cells due to the toxicity of the high concentrations of soluble arsenic and iron ions at low p H value should mainly response for the incomplete extraction at high pulp density. The initial bacterial community did not change in nature except for new found P aeruginosa ANSC, but sulfur-oxidizing microorganisms have been dominant microorganisms after a long time of adaptation. Pseudomonas aeruginosa originating from the gold concentrate should be closely relative to the metabolism of the organic matters contained in the refractory gold concentrate.
基金a grant(3/22775)from Ferdowsi University of Mashhad.
文摘Cellulose is the main structural component of lignocellulosic wastes that can be converted to sugars and biofuels by cellulase.Due to wide applications of this enzyme in various industries around the world,cellulase is considered as the third industrial enzyme.The ability of thermophilic bacteria in the production of heat-stable cellulases has made them valuable tools in biotechnology.The aim of this study was isolation and molecular identification of cellulolytic thermophile bacteria from Dig Rostam hot spring and investigating their cellulase activity.Samples were taken from water and sediments of this hot spring,and cellulolytic bacteria were enriched in media containing cellulose as the only carbon source.The bacteria were incubated at 60℃,and single colonies were then isolated on solid media.Congo red assay was used as a quick test for the qualitative screening of cellulase activity.According to these qualitative results,four colonies named CDB1,CDB2,CDB3,and CDB4 were isolated,and their growth curve and some other characteristics were determined by biochemical assays.Moreover,endoglucanase,exoglucanase,and FPase activities of the isolates were investigated quantitatively.Results indicated that CDB1 exhibited the highest endoglucanase(0.096 U/mL)and exoglucanase(0.156 U/mL)activities among other isolates.16S rDNA partial sequencing indicated that CDB1 had 99%similarity to the genus Anoxybacillus,and the other isolates showed the highest similarity to the genus Geobacillus.The cellulase gene of CDB1 isolate with the highest cellulase activity was also cloned,and its sequence is reported for the first time.Further studies on this thermophilic enzyme might be useful for industrial applications.
