The present study was aimed to assess the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr（Ⅵ）（4800 μg/mL） and ...The present study was aimed to assess the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr（Ⅵ）（4800 μg/mL） and S.capitis could tolerate Cr（Ⅵ）（2800 μg/mL）.Both organisms were able to resist Cd^2＋（50 μg/mL）,Cu^2＋（200 μg/mL）,Pb^2＋（800 μg/mL）,Hg^2＋（50 μg/mL） and Ni2＋（4000 μg/mL）.S.capitis resisted Zn^2＋ at 700 μg/mL while Bacillus sp.JDM-2-1 only showed resistance up to 50 μg/mL.Bacillus sp.JDM-2-1 and S.capitis showed optimum growth at pH 6 and 7,respectively,while both bacteria showed optimum growth at 37°C.Bacillus sp.JDM-2-1 and S.capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%,respectively,from the industrial effuents after 144 h.Cell free extracts of Bacillus sp.JDM-2-1 and S.capitis showed reduction of 83% and 70% at concentration of 10 μg Cr（Ⅵ）/mL,respectively.The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction.The bacterial isolates can be exploited for the bioremediation of hexavalent chromium containing wastes,since they seem to have a potential to reduce the toxic hexavalent form to its nontoxic trivalent form.展开更多
The experiments were conducted to evaluate the Cr(Ⅵ)resistance and reduction by Pseudomonas aeruginosa.After this bacterium tolerated 40 mg/L Cr(Ⅵ),the growth of cells was observed.The bacterial growth was obviously...The experiments were conducted to evaluate the Cr(Ⅵ)resistance and reduction by Pseudomonas aeruginosa.After this bacterium tolerated 40 mg/L Cr(Ⅵ),the growth of cells was observed.The bacterial growth was obviously lower than the controls over 24 h and the binary cell fission was observed in cell morphology by scanning electron microscope.P.aeruginosa was found to be able to reduce Cr(Ⅵ)although Cr(Ⅵ)had toxic effects on the cells.The results demonstrate that Cr(Ⅵ)is reduced from 40 mg/L to about 18 mg/L in 72 h.The value of pH drops from 7.02 to around 5.65 after 72 h.A significant increase in the value of redox potential occurs during Cr(Ⅵ)reduction and Cr(Ⅵ)reduction can be observed over a range of redox potential from+3 mV to+91 mV.Both of SO4 2-and NO3 -have no effect on Cr(Ⅵ)reduction.The presence of Zn 2+has a notable inhibitory effect on Cr(Ⅵ) reduction while Cu 2+ substantially stimulates Cr(Ⅵ)reduction.In the presence of Zn 2+ ,Cr(Ⅵ)decreases from 40 mg/L to only 26-27 mg/L,whereas Cr(Ⅵ)drops to 1-2 mg/L after 48 h in the presence of Cu2 +.展开更多
[Objective] The aim was to separate chromium-resistant microorganism from soil contaminated by chromium.[Method] Separation and purification technique was used as follows：different concentrations of Cr^6＋ were added...[Objective] The aim was to separate chromium-resistant microorganism from soil contaminated by chromium.[Method] Separation and purification technique was used as follows：different concentrations of Cr^6＋ were added into medium,and chromium-resistant fungi were screened after separations and domestications.The selected fungi were under preliminary identification according to its morphological and colony characteristics.Then,related biological characteristics were studied,including measurement of growth curve,growing effects by temperature,pH value and osmotic pressure.[Result] The Cr（VI） with concentration of 1 000 mg/L was separated and selected from soils in ten different places contaminated seriously by heavy metal in adjacent region of Yulin City.Considering its morphological and colony characteristics,it was preliminarily identified as saccharomycetes,which can well grow within 15-37 ℃,and whose most suitable temperature was 28℃.Bacterial strain can grow well with pH of 4-10,and the optimum pH was 7.2;besides,it can grow well with NaCl concentration of 0.5%-5.0%.Through the experiment,the bacteria was found with resistance not only to chromium,but also to heavy metals such as Pb＋Cu,Cu＋Fe,Pb＋Fe,and Pb＋Cu＋Fe.[Conclusion] The fungi selected from the experiment were of good adaptability to natural environment,and it also had resistance to other heavy metals.展开更多
文摘The present study was aimed to assess the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr（Ⅵ）（4800 μg/mL） and S.capitis could tolerate Cr（Ⅵ）（2800 μg/mL）.Both organisms were able to resist Cd^2＋（50 μg/mL）,Cu^2＋（200 μg/mL）,Pb^2＋（800 μg/mL）,Hg^2＋（50 μg/mL） and Ni2＋（4000 μg/mL）.S.capitis resisted Zn^2＋ at 700 μg/mL while Bacillus sp.JDM-2-1 only showed resistance up to 50 μg/mL.Bacillus sp.JDM-2-1 and S.capitis showed optimum growth at pH 6 and 7,respectively,while both bacteria showed optimum growth at 37°C.Bacillus sp.JDM-2-1 and S.capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%,respectively,from the industrial effuents after 144 h.Cell free extracts of Bacillus sp.JDM-2-1 and S.capitis showed reduction of 83% and 70% at concentration of 10 μg Cr（Ⅵ）/mL,respectively.The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction.The bacterial isolates can be exploited for the bioremediation of hexavalent chromium containing wastes,since they seem to have a potential to reduce the toxic hexavalent form to its nontoxic trivalent form.
基金Project(IRT0719)supported by the Program for Changjiang Scholars and Innovative Research Team in University,ChinaProjects(2006BAD03A1704,2006BAD03A1706)supported by the National Science&Technology Pillar Program during the 11th Five-year Plan Period of China
文摘The experiments were conducted to evaluate the Cr(Ⅵ)resistance and reduction by Pseudomonas aeruginosa.After this bacterium tolerated 40 mg/L Cr(Ⅵ),the growth of cells was observed.The bacterial growth was obviously lower than the controls over 24 h and the binary cell fission was observed in cell morphology by scanning electron microscope.P.aeruginosa was found to be able to reduce Cr(Ⅵ)although Cr(Ⅵ)had toxic effects on the cells.The results demonstrate that Cr(Ⅵ)is reduced from 40 mg/L to about 18 mg/L in 72 h.The value of pH drops from 7.02 to around 5.65 after 72 h.A significant increase in the value of redox potential occurs during Cr(Ⅵ)reduction and Cr(Ⅵ)reduction can be observed over a range of redox potential from+3 mV to+91 mV.Both of SO4 2-and NO3 -have no effect on Cr(Ⅵ)reduction.The presence of Zn 2+has a notable inhibitory effect on Cr(Ⅵ) reduction while Cu 2+ substantially stimulates Cr(Ⅵ)reduction.In the presence of Zn 2+ ,Cr(Ⅵ)decreases from 40 mg/L to only 26-27 mg/L,whereas Cr(Ⅵ)drops to 1-2 mg/L after 48 h in the presence of Cu2 +.
基金Supported by Chinese National Natural Science Foundation(30960008 )Educational Commission of Guangxi Province(200810LX393)+2 种基金Starting Project of Yulin Normal College,Guangxi ProvinceSpecialized Research Project of Yulin Normal College,Guangxi Province (2011YJZX01)Project Supported by the Science Foundation for Young Scientists of Guangxi Yulin Normal College (2010YJQN24)~~
文摘[Objective] The aim was to separate chromium-resistant microorganism from soil contaminated by chromium.[Method] Separation and purification technique was used as follows：different concentrations of Cr^6＋ were added into medium,and chromium-resistant fungi were screened after separations and domestications.The selected fungi were under preliminary identification according to its morphological and colony characteristics.Then,related biological characteristics were studied,including measurement of growth curve,growing effects by temperature,pH value and osmotic pressure.[Result] The Cr（VI） with concentration of 1 000 mg/L was separated and selected from soils in ten different places contaminated seriously by heavy metal in adjacent region of Yulin City.Considering its morphological and colony characteristics,it was preliminarily identified as saccharomycetes,which can well grow within 15-37 ℃,and whose most suitable temperature was 28℃.Bacterial strain can grow well with pH of 4-10,and the optimum pH was 7.2;besides,it can grow well with NaCl concentration of 0.5%-5.0%.Through the experiment,the bacteria was found with resistance not only to chromium,but also to heavy metals such as Pb＋Cu,Cu＋Fe,Pb＋Fe,and Pb＋Cu＋Fe.[Conclusion] The fungi selected from the experiment were of good adaptability to natural environment,and it also had resistance to other heavy metals.
