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
Forty-six candidate phenol/benzoate degrading-iron reducing bacteria were isolated from long term irrigated tropical paddy soils by enrichment procedures.Pure cultures and some prepared mixed cultures were examined fo...Forty-six candidate phenol/benzoate degrading-iron reducing bacteria were isolated from long term irrigated tropical paddy soils by enrichment procedures.Pure cultures and some prepared mixed cultures were examined for ferric oxide reduction and phenol/benzoate degradation.All the isolates were iron reducers,but only 56.5%could couple iron reduction to phenol and/or benzoate degradation,as evidenced by depletion of phenol and benzoate after one week incubation.Analysis of degradative capability using Biolog...展开更多
The study is aimed at the problem of high content of Cr^(6+),Cr^(3+)and SO_(4)^(2-)is high and low pH value in acid mine drainage(AMD).Moreover,treatment of AMD by sulfate reducing bacteria(SRB)requires the addition o...The study is aimed at the problem of high content of Cr^(6+),Cr^(3+)and SO_(4)^(2-)is high and low pH value in acid mine drainage(AMD).Moreover,treatment of AMD by sulfate reducing bacteria(SRB)requires the addition of carbon source,while the treating effectiveness is not good enough on its own.The sugarcane slag,the corn cob and the sunflower straw were selected as the SRB carbon source cooperating with iron scrap to construct the dynamic columns 1,2 and 3.The mechanism of removing Cr^(6+),Cr^(3+),SO_(4)^(2-)and H+and the regularity of sustained release of carbon source and TFe release was studied in AMD.The removal efficiency of heavy metal ions,the ability of sustained release of carbon source,and the ability of adjusting acid by the three dynamic columns were compared.The result shows that the average removal rates of Cr^(6+),Cr^(3+)and SO_(4)^(2-)in effluent of dynamic column 1,filled by sugarcane slag,iron scrap and SRB,were 96.9%,67.1%and 54.3%.The average release of TFe and chemical oxygen demand(COD)were 4.4 and 287.3 mg/L.Its average pH was 6.98.Compared with the performance of dynamic columns 1,2 and 3,dynamic column 1 performed best in removing Cr^(6+),Cr^(3+)and SO_(4)^(2-)from AMD and controlling the release of COD and TFe,adjusting the pH of the solution.The study is of significance in treatment of AMD by taking for biomass materials as SRB carbon source in cooperation with iron scrap.展开更多
The effect of sulfate reducing bacteria (SRB) on electrochemical corrosion behavior of 16Mn steel, and galvanic corrosion behavior of the steels in the juncture area between bacterial and bacteria free sea mud was stu...The effect of sulfate reducing bacteria (SRB) on electrochemical corrosion behavior of 16Mn steel, and galvanic corrosion behavior of the steels in the juncture area between bacterial and bacteria free sea mud was studied in laboratory under simulated conditions. Sea mud dense with SRB was taken from the Qingdao beach. Part of the sea mud was sterilized and the rest was kept in the original condition. The sterilized and original sea mud was put respectively into two plastic testing troughs electrically connected by an agar potassium chloride salt bridge. Galvanic and non galvanic 16Mn steel samples were put into the trough at the same intervals. The SRB number measured by the MPN tri tube method was about 2.4×10 5 per 100 g mud and was kept basically the same during the experimental period. The ρ, pH, eH, T, S (salinity) were measured simultaneously. The galvanic current was measured with zero resistance galvanometer and the corrosion rate was measured with the weight loss method.The results showed that (1) the corrosion rate of 16Mn steel in bacterial sea mud was 4.0 times that in bacteria free sea mud; (2) galvanic corrosion occurs between steel samples buried in different (bacterial and bacteria free) sea mud. The steel sample in the bacterial sea mud was the anode of a galvanic couple and had higher corrosion rate than that of the non galvanic sample. The existence of the galvanic couple increased the corrosion rate of the sample in bacterial sea mud by 4.1%.展开更多
A sulfate reducing bacteria was isolated from mining sewage of Daqing Oilfield by Hungate anaerobic technology. Physiological-biochemical analysis showed that the strain could utilize polyacrylamide as sole carbon and...A sulfate reducing bacteria was isolated from mining sewage of Daqing Oilfield by Hungate anaerobic technology. Physiological-biochemical analysis showed that the strain could utilize polyacrylamide as sole carbon and nitrogen source. The sequence analysis of 16S rDNA illustrated that the similarity of F8 and Desulfovibrio desulfuricans (AF192153) was 99%, and the similarity sequence of dissimilatory sulfite reductase gene (DSR) cloned from the strain and Desulfovibrio desulfuricans (AF273034) was 98%. Their phylogenitic analysis was basically anastomosed, and thus temporarily named as Desulfovibrio desulfuricans F8. The DSR cloned from F8 strain was 2740 bp in length consisting of three ORF, DSRA, DSRB and DSRD as a single operon (DSRABD) regulated by the same operator. DSRA contained typical conservative box of sulfate—sulfite reducing enzyme (SiteⅠand SiteⅡ), which could bind siroheme and [Fe4S4]. DSRB retained a [Fe4S4] binding site, with an uncomplimentary structure for siroheme binding. There was no conservative box in DSRD. Sequence analysis of DSR will provide a theoretical basis for quantitative detection, metabolic pathway modification through gene engineering, and sulfate reducing bacteria (SRB) suppression.展开更多
Microspheres of conducting polymers poly N-methylaniline (PNMA) were successfully synthesized through oxidation of N-methylaniline without any template. The average diameter of the microspheres with a smooth surface...Microspheres of conducting polymers poly N-methylaniline (PNMA) were successfully synthesized through oxidation of N-methylaniline without any template. The average diameter of the microspheres with a smooth surface was about 0.40 μm when 0.2 M N-methylanUine was oxidized with 0.2 M ammonium persulfate in 0.2 M of HClO4 solution. The size of microspheres can be controlled by changing reaction time and temperature. The acid concentration was critical for the formation of microspheres with smooth surfaces. The excellent antibacterial performance of PNMA in novolac epoxy coating to sulfate reducing bacteria was demonstrated. Moreover, in API media, PNMA inhibited growth of SRB and then reduced the corrosion rate of carbon steel remarkably.展开更多
Field and greenhouse experiments were conducted to investigate the effects of cropping season, nitrogen fertilizer input and aerated fallow on the dynamics of phenol degradihg-iron reducing bacteria (PD-IRB) in tropic...Field and greenhouse experiments were conducted to investigate the effects of cropping season, nitrogen fertilizer input and aerated fallow on the dynamics of phenol degradihg-iron reducing bacteria (PD-IRB) in tropical irrigated rice (Oryza sativa L.) systems. The PD-IRB population density was monitored at different stages of rice growth in two cropping seasons (dry and early wet) in a continuous annual triple rice cropping system under irrigated condition. In this system, the high nitrogen input (195 and 135 kg N ha-1 in dry and wet seasons, respectively) plots and control plots receiving no N fertilizer were compared to investigate the effect of nitrogen rate on population size. The phenol degrading-iron reducing bacteria (PD-IRB) were abundant in soils under cropping systems of tropical irrigated rice. However, density of the bacterial populations varied with rice growth stages. Cropping seasons, rhizosphere, and aerated fallow could affect the dynamics of PD-IRB. In the field trial, viable counts of PD-IRB in the topsoil layer (15 cm) ranged between 102 and 108 cells per gram of dry soil, A steep increase in viable counts during the second half of the cropping season suggested that the population density of PD-IRB increased at advanced crop-growth stages. Population growth of PD-IRB was accelerated during the dry season compared to the wet season. In the greenhouse experiment, the adjacent aerated fallow revealed 1-2 orders of magnitude higher in most probable number (MPN) of PD-IRB than the wet fallow treated plots. As a prominent group Of Fe reducing bacteria, PD-IRB predominated in the rhizosphere of rice, since maximum MPN of PD-IRB (2.62×108 g-1 soil) was found in rhizosphere soil. Mineral N fertilizer rates showed no significant effect on PD-IRB population density.展开更多
<Abstrat>The surface sediment samples were collected month by month at nine stations in the Daya Bay from January to December 1987, and the number of anaerobic sulfite reducing bacteria and their spores and the ...<Abstrat>The surface sediment samples were collected month by month at nine stations in the Daya Bay from January to December 1987, and the number of anaerobic sulfite reducing bacteria and their spores and the regularity of seasonal change were determined. The effect of environmental factors, water temperature and the resoluble oxygen concentration in the bottom of seawater on the number of them were discussed. The results show that the number of anaerobic su|fite reducing bacteria were low in sediment of the Daya Bay, indicating that the hay was less contaminated.展开更多
Rice is one of the staple crops in Burkina Faso. However, the local production covers only 47% of the population demands. One of the main reasons of the poor productivity in Burkina Faso is iron toxicity which is rela...Rice is one of the staple crops in Burkina Faso. However, the local production covers only 47% of the population demands. One of the main reasons of the poor productivity in Burkina Faso is iron toxicity which is related mainly to the activity of Iron Reducing Bacteria in the rice field’s ecosystems. In order to control the harmful effects of Iron Reducing Bacterial populations and to improve rice productivity, a pots experiment was conducted at the experimental site of the University Ouaga I Pr. Joseph KI-ZERBO. An iron toxic soil from Kou Valley (West of Burkina Faso) and two rice varieties, BOUAKE-189 and ROK-5, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were drained for 14 days (D2) and amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complexes). Control pots without drainage and fertilization (D0/NF) were prepared similarly. The kinetics of Iron Reducing Bacterial populations and ferrous iron content in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. The total iron content was evaluated in rice plant using a spectrometric method. Data obtained were analyzed in relation to drainage and fertilization mode, rice growth stage and rice yield using the Student’s t-test and XLSTAT 2014 statistical software. The experiment showed that the combined application of subsurface drainage and NPK + Urea + Ca + Mg + Zn fertilization, reduced significantly the number of IRB in the soil near rice roots for both rice varieties (p = 0.050 and p = 0.020) increased the leaf tissue tolerance to excess amounts of Fe, and rice yield.展开更多
A process of treatment for containing Cd 2+ wastewater by sulfate reducing bacteria with upflow anaerobic fluidized bed reactor has been studied. When the concentration of COD and Cd 2+ in the influent were...A process of treatment for containing Cd 2+ wastewater by sulfate reducing bacteria with upflow anaerobic fluidized bed reactor has been studied. When the concentration of COD and Cd 2+ in the influent were 270 5mg/L and 100mg/L respectively and hydraulic retention time was 4 hours, the removal rate of COD and Cd 2+ were higher than 73 8% and 99 8% respectively. The reactor can treat as high as 1000mg/L of concentration of Cd 2+ . The highest removal velocity rate of Cd 2+ reached 2999 1mg/(L·d). And the possible relationship between sulfate reducing bacteria and methanogenic bacteria was discussed.展开更多
This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria (SRB) on stainless steel 316L (SS316L) surface in circulating cooling water system with and without additives including...This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria (SRB) on stainless steel 316L (SS316L) surface in circulating cooling water system with and without additives including hydroxy ethyl fork phosphonic acid (HEDP), dodecyl dimethyl benzyl anunonium chlotide (1227) and NaClO. Biochemical technique, electrochemical technology, X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used. The results show that the extracellular polymeric substance (EPS) in biofilm attached on the SS316L surface mainly contain proteins and polysaccharides, the contents are 98 ug.cm-2 and 635ug.cm-2, respectively. The polysaccharides were cut by 1227 about 80%, while 55% by NaCIO. The proteins were reduced by NaCIO about 53%, while only 30% by 1227. The potentiodynamic polarization shows that the corrosion potential of SS316L was enhanced from -0.495 V to -0.390 V by the chemical additive delaying the occurrence of the corrosion. And the corrosion rate was also reduced from 5.19 × 10^-3 mm·a^-1 to 2.42 × 10^-3 mm'a . But NaCIO stdl caused pitting corrosion after stenhzmg the bacteria, while 1227 can form a protective film on the surface of SS316L. Though HEDP contribute to the bacteria activity, it can enhance the breakdown potential. XPS results confirmed that 1227 can change the value of C:O in the biofilm attached on metal surface, and NaCIO can eliminate the existence of amidogen. This study would provide some recommendations for the selection of chemical additives in the thermal power plant.展开更多
Sulfate reducing bacteria(SRB) play significant roles in anaerobic environments in oil sands mature fine tailings(MFTs). Hydrogen sulfide(H2S) is produced during the biological sulfate reduction process. The pro...Sulfate reducing bacteria(SRB) play significant roles in anaerobic environments in oil sands mature fine tailings(MFTs). Hydrogen sulfide(H2S) is produced during the biological sulfate reduction process. The production of toxic H2S is one of the concerns because it may hinder the landscape remediation efficiency of oil sands tailing ponds. In present study, the in situ activity and the community structure of SRB in MFT and gypsum amended MFT in two settling columns were investigated. Combined techniques of H2S microsensor and dissimilatory sulfite reductase β-subunit(dsrB) genes-based real time quantitative polymerase chain reaction(qPCR) were applied to detect the in situ H2S and the abundance of SRB. A higher diversity of SRB and more H2S were observed in gypsum amended MFT than that in MFT, indicating a higher sulfate reduction activity in gypsum amended MFT; in addition, the activity of SRB varied as depth in both MFT and gypsum amended MFT: the deeper the more H2S produced. Long-term plans for tailings management can be assessed more wisely with the information provided in this study.展开更多
The membrane-associated c-type cytochromes(c-Cyts) have been well known as the key enzymes mediating extracellular electron transfer to terminal electron acceptors, resulting in biogeochemical elemental transformation...The membrane-associated c-type cytochromes(c-Cyts) have been well known as the key enzymes mediating extracellular electron transfer to terminal electron acceptors, resulting in biogeochemical elemental transformation, contaminant degradation, and nutrient cycling. Although c-Cyts-mediated metal reduction or oxidation have been mainly investigated with the purified proteins of metal reducing/oxidizing bacteria, the in vivo behavior of c-Cyts is still unclear, given the difficulty in measuring the proteins of intact cells. Fortunately, the in situ spectroscopy would be ideal for measuring the reaction kinetics of c-Cyts in intact cells under noninvasive physiological conditions. It can also help the establishment of kinetic/thermodynamic models of extracellular electron transfer processes, which are essential to understand the electron transfer mechanisms at the molecular scale. This review briefly summarizes the current advances in spectral methods for examining the c-Cyts in intact cells of dissimilatory metal reducing bacteria and Fe(Ⅱ)-oxidizing bacteria.展开更多
The biosorption properties of dead sulfate reducing bacteria (SRB) for the removal of Cu(Ⅱ) and Fe(Ⅲ) from aqueous solutions was studied. The effects of the biosorbent concentration, the initial pH value and t...The biosorption properties of dead sulfate reducing bacteria (SRB) for the removal of Cu(Ⅱ) and Fe(Ⅲ) from aqueous solutions was studied. The effects of the biosorbent concentration, the initial pH value and the temperature on the biosorption of Cu(Ⅱ) and Fe(Ⅲ) by the SRB were investigated. FTIR analysis verified that the hydroxyl, carbonyl and amine functional groups of the SRB biosorbent were involved in the biosorption process. For both Cu(Ⅱ) and Fe(Ⅲ), an increase in the SRB biosorbent concentration resulted in an increase in the removal percentage but a decrease in the amount of specific metal biosorption. The maximum specific metal biosorption was 93.25 mg·g^-1 at pH 4.5 for Cu(Ⅱ) and 88.29 mg· g^-1 at pH 3.5 for Fe(Ⅲ). The temperature did not have a significant effect on biosorption. In a binary metal system, the specific biosorption capacity for the target metal decreased when another metal ion was added. For both the single metal and binary metal systems, the biosorption of Cu(Ⅱ) and Fe(Ⅲ) onto a SRB biosorbent was better represented by a Langmuir model than by a Freundlich model.展开更多
The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first t...The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe(II) concentration with the treatment of anthraquinone-2, 6-disulfonic acid (AQDS) and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with the iron reduction, and a significant correlation between Fe(II) and total As in culture was observed. However, compared with control, the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations of As(III) and As(V) in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.展开更多
The relationships between the phosphine content and various microbial populations,activities of different enzymes were investigated firstly.The results indicated that the phosphine content of samples from various envi...The relationships between the phosphine content and various microbial populations,activities of different enzymes were investigated firstly.The results indicated that the phosphine content of samples from various environments was positively related to total anaerobic microorganisms,organic phosphate compound-dissolving bacteria,denitrifying bacteria,and the activities of alkaline phosphatase and dehydrogenase,with correlation coefficients (R^2) up to 0.93,0.90,0.69,0.79,and 0.82,respectively.Results also sh...展开更多
Technological advances in the past 30 years have boosted the use of PSM (membrane separation processes), important for its efficiency and flexibility of operation. These processes can be used in many types of separa...Technological advances in the past 30 years have boosted the use of PSM (membrane separation processes), important for its efficiency and flexibility of operation. These processes can be used in many types of separation, with some advantages over the usual separation processes. NF (nanofiltration) is a membrane separation technique, which has properties intermediate between reverse osmosis and ultrafiltration in terms of separated species, because the average of the pores is in the range of 1/2 to 10 nm, and the separation occurs in function of load and size of the species. Usually removes species in solution with an effective diameter of about 1 nm or larger and multivalent ions to a greater extent than monovalent ions. The objective was to study the formation of biofouling on the surface of commercial nanofiltration membrane (Osmonics/GE) and surface membrane synthesized in our laboratory. The study was conducted in permeation system with filtration cell with tangential displacement of 15 bar for 8 days flow. DBNPA (2,2-dibromo-3-nitrilopropionamide) was used as a biocide agent, and an anti-fouling, in concentrations of 5 and 300 ppm, respectively, added to the water coming from the Beach Sea Galleon, RJ. The results demonstrated that there was no change in the flow and rejection of sulphate ions, even in the presence of anti-fouling. The count of aerobic, anaerobic and BRS (sulfate reducing bacteria) in seawater before and after using the DBNPA showed efficiency in controlling these groups of microorganisms and biofouling microbial consortium consisting of the existing in seawater.展开更多
Sulfate reducing bacteria were isolated from the soil sample of Roaster-Acid unit of Debari Zinc Smelter of Hindustan Zinc Ltd., India and were adapted for effluent water of Zinc hydrometallurgy plant to sustain zinc ...Sulfate reducing bacteria were isolated from the soil sample of Roaster-Acid unit of Debari Zinc Smelter of Hindustan Zinc Ltd., India and were adapted for effluent water of Zinc hydrometallurgy plant to sustain zinc concentration of about 500 ppm and iron concentration of about 160 ppm with high acidity (pH 〈 1.0). Nutrient broth, whey, ethanol and sucrose were tested as carbon source for SRB (sulfate reducing bacteria) out of which whey was found as the best electron donor to expedite the rate of biological treatment with SRB. A two stage anaerobic bioreactor was developed with a treatment capacity of 30 L effluent water in 4 days. The concentration of heavy metals in the treated water was within the permissible limits. The suggested methodology generates no solid waste, is environment friendly and may be commercially implemented for treatment of zinc plant effluent.展开更多
Sulfate reducing bacteria(SRB)are widely present in oil and gas industry,causing pitting corrosion on pipeline steel.Stress corrosion cracking(SCC)often occurs in the presence of mechanical stress before pit-ting perf...Sulfate reducing bacteria(SRB)are widely present in oil and gas industry,causing pitting corrosion on pipeline steel.Stress corrosion cracking(SCC)often occurs in the presence of mechanical stress before pit-ting perforation failure,leading to economic losses and even catastrophic accidents.In this study,stress distribution simulation using the finite element method(FEM),corrosion analysis techniques and elec-trochemical corrosion measurements were employed to investigate the SCC mechanism of X80 pipeline steel caused by Desulfovibrio vulgaris,which is a common SRB strain used in microbiologically influenced corrosion(MIC)studies.It was found that D.vulgaris MIC caused sharp microcracks on an X80 U-bend coupon after only 2 weeks of immersion at 37℃in the deoxygenated ATCC 1249 culture medium inocu-lated with D.vulgaris.The X80 U-bend coupon’s weight loss-based uniform corrosion rate for the 12 cm^(2)surface was 60%of that for the unstressed flat square coupon(2.3 mg cm^(−2)vs.3.8 mg cm^(−2)).This was likely because the square coupon had wide MIC pits,providing a larger effective surface area for more sessile cells(4.2×10^(8)cells cm^(−2)on square coupon vs.2.4×10^(8)cells cm^(−2)on U-bend coupon)to attach and harvest more electrons.An SCC failure occurred on an X80 U-bend pre-cracked at the outer bottom after a 6-week immersion in the D.vulgaris broth.Apart from MIC damage,this could also be because D.vulgaris metabolism increased the availability hydrogen atoms on the steel surface,and promoted the diffusion of hydrogen atoms into the metal lattice,thus increasing the brittleness of the steel.展开更多
The microbiologically influenced corrosion(MIC) mechanisms of copper by Pseudomonas aeruginosa as a typical strain of nitrate reducing bacteria(NRB) was investigated in this lab study.Cu was immersed in deoxygenated L...The microbiologically influenced corrosion(MIC) mechanisms of copper by Pseudomonas aeruginosa as a typical strain of nitrate reducing bacteria(NRB) was investigated in this lab study.Cu was immersed in deoxygenated LB-NO3 seawater inoculated with P.aeruginosa and incubated for 2 weeks.Results showed that this NRB caused pitting and uniform corrosion.The maximum pit depths after 7 d and 14 d in125 mL anaerobic vials with 50 mL broth were 5.1 μm and 9.1 μm,accompanied by specific weight losses of 1.3 mg/cm2(7 d) and 1.7 mg/cm2(14 d),respectively.Electrochemical measurements corroborated weight loss and pit depth data trends.Experimental results indicated that extracellular electron transfer for nitrate reduction was the main MIC mechanism and ammonia secreted by P.aeruginosa could also play a role in the overall Cu corrosion process.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.
文摘Forty-six candidate phenol/benzoate degrading-iron reducing bacteria were isolated from long term irrigated tropical paddy soils by enrichment procedures.Pure cultures and some prepared mixed cultures were examined for ferric oxide reduction and phenol/benzoate degradation.All the isolates were iron reducers,but only 56.5%could couple iron reduction to phenol and/or benzoate degradation,as evidenced by depletion of phenol and benzoate after one week incubation.Analysis of degradative capability using Biolog...
基金This work was supported by the National Natural Science Foundation of China(41672247,41102157)Liaoning Province’s“Program for Promoting Liaoning Talents”(XLYC1807159)+1 种基金2019 Nature Fund Project Guidance Plan of Liaoning Province(2019-zd-0044)2017 Youth Project of Education Department of Liaoning Province(LJ2017QL035).
文摘The study is aimed at the problem of high content of Cr^(6+),Cr^(3+)and SO_(4)^(2-)is high and low pH value in acid mine drainage(AMD).Moreover,treatment of AMD by sulfate reducing bacteria(SRB)requires the addition of carbon source,while the treating effectiveness is not good enough on its own.The sugarcane slag,the corn cob and the sunflower straw were selected as the SRB carbon source cooperating with iron scrap to construct the dynamic columns 1,2 and 3.The mechanism of removing Cr^(6+),Cr^(3+),SO_(4)^(2-)and H+and the regularity of sustained release of carbon source and TFe release was studied in AMD.The removal efficiency of heavy metal ions,the ability of sustained release of carbon source,and the ability of adjusting acid by the three dynamic columns were compared.The result shows that the average removal rates of Cr^(6+),Cr^(3+)and SO_(4)^(2-)in effluent of dynamic column 1,filled by sugarcane slag,iron scrap and SRB,were 96.9%,67.1%and 54.3%.The average release of TFe and chemical oxygen demand(COD)were 4.4 and 287.3 mg/L.Its average pH was 6.98.Compared with the performance of dynamic columns 1,2 and 3,dynamic column 1 performed best in removing Cr^(6+),Cr^(3+)and SO_(4)^(2-)from AMD and controlling the release of COD and TFe,adjusting the pH of the solution.The study is of significance in treatment of AMD by taking for biomass materials as SRB carbon source in cooperation with iron scrap.
基金supported by the"Ninth-Five Plan"Great Project of the Chinese Academy of Sciences(KZ951-A1-405-04).
文摘The effect of sulfate reducing bacteria (SRB) on electrochemical corrosion behavior of 16Mn steel, and galvanic corrosion behavior of the steels in the juncture area between bacterial and bacteria free sea mud was studied in laboratory under simulated conditions. Sea mud dense with SRB was taken from the Qingdao beach. Part of the sea mud was sterilized and the rest was kept in the original condition. The sterilized and original sea mud was put respectively into two plastic testing troughs electrically connected by an agar potassium chloride salt bridge. Galvanic and non galvanic 16Mn steel samples were put into the trough at the same intervals. The SRB number measured by the MPN tri tube method was about 2.4×10 5 per 100 g mud and was kept basically the same during the experimental period. The ρ, pH, eH, T, S (salinity) were measured simultaneously. The galvanic current was measured with zero resistance galvanometer and the corrosion rate was measured with the weight loss method.The results showed that (1) the corrosion rate of 16Mn steel in bacterial sea mud was 4.0 times that in bacteria free sea mud; (2) galvanic corrosion occurs between steel samples buried in different (bacterial and bacteria free) sea mud. The steel sample in the bacterial sea mud was the anode of a galvanic couple and had higher corrosion rate than that of the non galvanic sample. The existence of the galvanic couple increased the corrosion rate of the sample in bacterial sea mud by 4.1%.
基金Sponsored by the National Basic Research and Development (973) Program of China(Grant No.2004CB418505)
文摘A sulfate reducing bacteria was isolated from mining sewage of Daqing Oilfield by Hungate anaerobic technology. Physiological-biochemical analysis showed that the strain could utilize polyacrylamide as sole carbon and nitrogen source. The sequence analysis of 16S rDNA illustrated that the similarity of F8 and Desulfovibrio desulfuricans (AF192153) was 99%, and the similarity sequence of dissimilatory sulfite reductase gene (DSR) cloned from the strain and Desulfovibrio desulfuricans (AF273034) was 98%. Their phylogenitic analysis was basically anastomosed, and thus temporarily named as Desulfovibrio desulfuricans F8. The DSR cloned from F8 strain was 2740 bp in length consisting of three ORF, DSRA, DSRB and DSRD as a single operon (DSRABD) regulated by the same operator. DSRA contained typical conservative box of sulfate—sulfite reducing enzyme (SiteⅠand SiteⅡ), which could bind siroheme and [Fe4S4]. DSRB retained a [Fe4S4] binding site, with an uncomplimentary structure for siroheme binding. There was no conservative box in DSRD. Sequence analysis of DSR will provide a theoretical basis for quantitative detection, metabolic pathway modification through gene engineering, and sulfate reducing bacteria (SRB) suppression.
基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education MinistryNatural Science Foundation of Hubei Province of China(No.2006ABA078)
文摘Microspheres of conducting polymers poly N-methylaniline (PNMA) were successfully synthesized through oxidation of N-methylaniline without any template. The average diameter of the microspheres with a smooth surface was about 0.40 μm when 0.2 M N-methylanUine was oxidized with 0.2 M ammonium persulfate in 0.2 M of HClO4 solution. The size of microspheres can be controlled by changing reaction time and temperature. The acid concentration was critical for the formation of microspheres with smooth surfaces. The excellent antibacterial performance of PNMA in novolac epoxy coating to sulfate reducing bacteria was demonstrated. Moreover, in API media, PNMA inhibited growth of SRB and then reduced the corrosion rate of carbon steel remarkably.
基金Project(No.IR021-00-0129-00)supported by the international Rice Research Institute (IRRI), Los Banos,Philippines.
文摘Field and greenhouse experiments were conducted to investigate the effects of cropping season, nitrogen fertilizer input and aerated fallow on the dynamics of phenol degradihg-iron reducing bacteria (PD-IRB) in tropical irrigated rice (Oryza sativa L.) systems. The PD-IRB population density was monitored at different stages of rice growth in two cropping seasons (dry and early wet) in a continuous annual triple rice cropping system under irrigated condition. In this system, the high nitrogen input (195 and 135 kg N ha-1 in dry and wet seasons, respectively) plots and control plots receiving no N fertilizer were compared to investigate the effect of nitrogen rate on population size. The phenol degrading-iron reducing bacteria (PD-IRB) were abundant in soils under cropping systems of tropical irrigated rice. However, density of the bacterial populations varied with rice growth stages. Cropping seasons, rhizosphere, and aerated fallow could affect the dynamics of PD-IRB. In the field trial, viable counts of PD-IRB in the topsoil layer (15 cm) ranged between 102 and 108 cells per gram of dry soil, A steep increase in viable counts during the second half of the cropping season suggested that the population density of PD-IRB increased at advanced crop-growth stages. Population growth of PD-IRB was accelerated during the dry season compared to the wet season. In the greenhouse experiment, the adjacent aerated fallow revealed 1-2 orders of magnitude higher in most probable number (MPN) of PD-IRB than the wet fallow treated plots. As a prominent group Of Fe reducing bacteria, PD-IRB predominated in the rhizosphere of rice, since maximum MPN of PD-IRB (2.62×108 g-1 soil) was found in rhizosphere soil. Mineral N fertilizer rates showed no significant effect on PD-IRB population density.
文摘<Abstrat>The surface sediment samples were collected month by month at nine stations in the Daya Bay from January to December 1987, and the number of anaerobic sulfite reducing bacteria and their spores and the regularity of seasonal change were determined. The effect of environmental factors, water temperature and the resoluble oxygen concentration in the bottom of seawater on the number of them were discussed. The results show that the number of anaerobic su|fite reducing bacteria were low in sediment of the Daya Bay, indicating that the hay was less contaminated.
文摘Rice is one of the staple crops in Burkina Faso. However, the local production covers only 47% of the population demands. One of the main reasons of the poor productivity in Burkina Faso is iron toxicity which is related mainly to the activity of Iron Reducing Bacteria in the rice field’s ecosystems. In order to control the harmful effects of Iron Reducing Bacterial populations and to improve rice productivity, a pots experiment was conducted at the experimental site of the University Ouaga I Pr. Joseph KI-ZERBO. An iron toxic soil from Kou Valley (West of Burkina Faso) and two rice varieties, BOUAKE-189 and ROK-5, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were drained for 14 days (D2) and amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complexes). Control pots without drainage and fertilization (D0/NF) were prepared similarly. The kinetics of Iron Reducing Bacterial populations and ferrous iron content in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. The total iron content was evaluated in rice plant using a spectrometric method. Data obtained were analyzed in relation to drainage and fertilization mode, rice growth stage and rice yield using the Student’s t-test and XLSTAT 2014 statistical software. The experiment showed that the combined application of subsurface drainage and NPK + Urea + Ca + Mg + Zn fertilization, reduced significantly the number of IRB in the soil near rice roots for both rice varieties (p = 0.050 and p = 0.020) increased the leaf tissue tolerance to excess amounts of Fe, and rice yield.
文摘A process of treatment for containing Cd 2+ wastewater by sulfate reducing bacteria with upflow anaerobic fluidized bed reactor has been studied. When the concentration of COD and Cd 2+ in the influent were 270 5mg/L and 100mg/L respectively and hydraulic retention time was 4 hours, the removal rate of COD and Cd 2+ were higher than 73 8% and 99 8% respectively. The reactor can treat as high as 1000mg/L of concentration of Cd 2+ . The highest removal velocity rate of Cd 2+ reached 2999 1mg/(L·d). And the possible relationship between sulfate reducing bacteria and methanogenic bacteria was discussed.
基金Acknowledgements The authors would like to acknowledge the financial support in a grant from the National Natural Science Foundation of China (Grant No. 51278035).
文摘This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria (SRB) on stainless steel 316L (SS316L) surface in circulating cooling water system with and without additives including hydroxy ethyl fork phosphonic acid (HEDP), dodecyl dimethyl benzyl anunonium chlotide (1227) and NaClO. Biochemical technique, electrochemical technology, X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used. The results show that the extracellular polymeric substance (EPS) in biofilm attached on the SS316L surface mainly contain proteins and polysaccharides, the contents are 98 ug.cm-2 and 635ug.cm-2, respectively. The polysaccharides were cut by 1227 about 80%, while 55% by NaCIO. The proteins were reduced by NaCIO about 53%, while only 30% by 1227. The potentiodynamic polarization shows that the corrosion potential of SS316L was enhanced from -0.495 V to -0.390 V by the chemical additive delaying the occurrence of the corrosion. And the corrosion rate was also reduced from 5.19 × 10^-3 mm·a^-1 to 2.42 × 10^-3 mm'a . But NaCIO stdl caused pitting corrosion after stenhzmg the bacteria, while 1227 can form a protective film on the surface of SS316L. Though HEDP contribute to the bacteria activity, it can enhance the breakdown potential. XPS results confirmed that 1227 can change the value of C:O in the biofilm attached on metal surface, and NaCIO can eliminate the existence of amidogen. This study would provide some recommendations for the selection of chemical additives in the thermal power plant.
基金financial supports from Natural Sciences and Engineering Research Council (NSERC) of CanadaCanadian School of Energy and the Environment (CSEE)China Scholarship Council (CSC)
文摘Sulfate reducing bacteria(SRB) play significant roles in anaerobic environments in oil sands mature fine tailings(MFTs). Hydrogen sulfide(H2S) is produced during the biological sulfate reduction process. The production of toxic H2S is one of the concerns because it may hinder the landscape remediation efficiency of oil sands tailing ponds. In present study, the in situ activity and the community structure of SRB in MFT and gypsum amended MFT in two settling columns were investigated. Combined techniques of H2S microsensor and dissimilatory sulfite reductase β-subunit(dsrB) genes-based real time quantitative polymerase chain reaction(qPCR) were applied to detect the in situ H2S and the abundance of SRB. A higher diversity of SRB and more H2S were observed in gypsum amended MFT than that in MFT, indicating a higher sulfate reduction activity in gypsum amended MFT; in addition, the activity of SRB varied as depth in both MFT and gypsum amended MFT: the deeper the more H2S produced. Long-term plans for tailings management can be assessed more wisely with the information provided in this study.
基金funded by the National Natural Science Foundations of China(41522105 and 41571130052)Guangdong Natural Science Funds for Distinguished Young Scholar(2014A030306041)Special Support Program(2016)
文摘The membrane-associated c-type cytochromes(c-Cyts) have been well known as the key enzymes mediating extracellular electron transfer to terminal electron acceptors, resulting in biogeochemical elemental transformation, contaminant degradation, and nutrient cycling. Although c-Cyts-mediated metal reduction or oxidation have been mainly investigated with the purified proteins of metal reducing/oxidizing bacteria, the in vivo behavior of c-Cyts is still unclear, given the difficulty in measuring the proteins of intact cells. Fortunately, the in situ spectroscopy would be ideal for measuring the reaction kinetics of c-Cyts in intact cells under noninvasive physiological conditions. It can also help the establishment of kinetic/thermodynamic models of extracellular electron transfer processes, which are essential to understand the electron transfer mechanisms at the molecular scale. This review briefly summarizes the current advances in spectral methods for examining the c-Cyts in intact cells of dissimilatory metal reducing bacteria and Fe(Ⅱ)-oxidizing bacteria.
文摘The biosorption properties of dead sulfate reducing bacteria (SRB) for the removal of Cu(Ⅱ) and Fe(Ⅲ) from aqueous solutions was studied. The effects of the biosorbent concentration, the initial pH value and the temperature on the biosorption of Cu(Ⅱ) and Fe(Ⅲ) by the SRB were investigated. FTIR analysis verified that the hydroxyl, carbonyl and amine functional groups of the SRB biosorbent were involved in the biosorption process. For both Cu(Ⅱ) and Fe(Ⅲ), an increase in the SRB biosorbent concentration resulted in an increase in the removal percentage but a decrease in the amount of specific metal biosorption. The maximum specific metal biosorption was 93.25 mg·g^-1 at pH 4.5 for Cu(Ⅱ) and 88.29 mg· g^-1 at pH 3.5 for Fe(Ⅲ). The temperature did not have a significant effect on biosorption. In a binary metal system, the specific biosorption capacity for the target metal decreased when another metal ion was added. For both the single metal and binary metal systems, the biosorption of Cu(Ⅱ) and Fe(Ⅲ) onto a SRB biosorbent was better represented by a Langmuir model than by a Freundlich model.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences(No. KZCX1-YW-06-03)
文摘The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe(II) concentration with the treatment of anthraquinone-2, 6-disulfonic acid (AQDS) and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with the iron reduction, and a significant correlation between Fe(II) and total As in culture was observed. However, compared with control, the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations of As(III) and As(V) in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.
文摘The relationships between the phosphine content and various microbial populations,activities of different enzymes were investigated firstly.The results indicated that the phosphine content of samples from various environments was positively related to total anaerobic microorganisms,organic phosphate compound-dissolving bacteria,denitrifying bacteria,and the activities of alkaline phosphatase and dehydrogenase,with correlation coefficients (R^2) up to 0.93,0.90,0.69,0.79,and 0.82,respectively.Results also sh...
文摘Technological advances in the past 30 years have boosted the use of PSM (membrane separation processes), important for its efficiency and flexibility of operation. These processes can be used in many types of separation, with some advantages over the usual separation processes. NF (nanofiltration) is a membrane separation technique, which has properties intermediate between reverse osmosis and ultrafiltration in terms of separated species, because the average of the pores is in the range of 1/2 to 10 nm, and the separation occurs in function of load and size of the species. Usually removes species in solution with an effective diameter of about 1 nm or larger and multivalent ions to a greater extent than monovalent ions. The objective was to study the formation of biofouling on the surface of commercial nanofiltration membrane (Osmonics/GE) and surface membrane synthesized in our laboratory. The study was conducted in permeation system with filtration cell with tangential displacement of 15 bar for 8 days flow. DBNPA (2,2-dibromo-3-nitrilopropionamide) was used as a biocide agent, and an anti-fouling, in concentrations of 5 and 300 ppm, respectively, added to the water coming from the Beach Sea Galleon, RJ. The results demonstrated that there was no change in the flow and rejection of sulphate ions, even in the presence of anti-fouling. The count of aerobic, anaerobic and BRS (sulfate reducing bacteria) in seawater before and after using the DBNPA showed efficiency in controlling these groups of microorganisms and biofouling microbial consortium consisting of the existing in seawater.
文摘Sulfate reducing bacteria were isolated from the soil sample of Roaster-Acid unit of Debari Zinc Smelter of Hindustan Zinc Ltd., India and were adapted for effluent water of Zinc hydrometallurgy plant to sustain zinc concentration of about 500 ppm and iron concentration of about 160 ppm with high acidity (pH 〈 1.0). Nutrient broth, whey, ethanol and sucrose were tested as carbon source for SRB (sulfate reducing bacteria) out of which whey was found as the best electron donor to expedite the rate of biological treatment with SRB. A two stage anaerobic bioreactor was developed with a treatment capacity of 30 L effluent water in 4 days. The concentration of heavy metals in the treated water was within the permissible limits. The suggested methodology generates no solid waste, is environment friendly and may be commercially implemented for treatment of zinc plant effluent.
基金supported by National Natural Science Foundation of China(No.U2106206)Institute of Marine Science and Technology,Shandong Univer-sity,China.
文摘Sulfate reducing bacteria(SRB)are widely present in oil and gas industry,causing pitting corrosion on pipeline steel.Stress corrosion cracking(SCC)often occurs in the presence of mechanical stress before pit-ting perforation failure,leading to economic losses and even catastrophic accidents.In this study,stress distribution simulation using the finite element method(FEM),corrosion analysis techniques and elec-trochemical corrosion measurements were employed to investigate the SCC mechanism of X80 pipeline steel caused by Desulfovibrio vulgaris,which is a common SRB strain used in microbiologically influenced corrosion(MIC)studies.It was found that D.vulgaris MIC caused sharp microcracks on an X80 U-bend coupon after only 2 weeks of immersion at 37℃in the deoxygenated ATCC 1249 culture medium inocu-lated with D.vulgaris.The X80 U-bend coupon’s weight loss-based uniform corrosion rate for the 12 cm^(2)surface was 60%of that for the unstressed flat square coupon(2.3 mg cm^(−2)vs.3.8 mg cm^(−2)).This was likely because the square coupon had wide MIC pits,providing a larger effective surface area for more sessile cells(4.2×10^(8)cells cm^(−2)on square coupon vs.2.4×10^(8)cells cm^(−2)on U-bend coupon)to attach and harvest more electrons.An SCC failure occurred on an X80 U-bend pre-cracked at the outer bottom after a 6-week immersion in the D.vulgaris broth.Apart from MIC damage,this could also be because D.vulgaris metabolism increased the availability hydrogen atoms on the steel surface,and promoted the diffusion of hydrogen atoms into the metal lattice,thus increasing the brittleness of the steel.
基金supported by China Postdoctoral Science Foundation (Grant Nos. 2019T120610 and 2018M640655)Open Fund of Shandong Key Laboratory of Corrosion Science (Grant No. KLCS201903)National Natural Science Foundation of China (Grant Nos. 51572249 and U1806223)。
文摘The microbiologically influenced corrosion(MIC) mechanisms of copper by Pseudomonas aeruginosa as a typical strain of nitrate reducing bacteria(NRB) was investigated in this lab study.Cu was immersed in deoxygenated LB-NO3 seawater inoculated with P.aeruginosa and incubated for 2 weeks.Results showed that this NRB caused pitting and uniform corrosion.The maximum pit depths after 7 d and 14 d in125 mL anaerobic vials with 50 mL broth were 5.1 μm and 9.1 μm,accompanied by specific weight losses of 1.3 mg/cm2(7 d) and 1.7 mg/cm2(14 d),respectively.Electrochemical measurements corroborated weight loss and pit depth data trends.Experimental results indicated that extracellular electron transfer for nitrate reduction was the main MIC mechanism and ammonia secreted by P.aeruginosa could also play a role in the overall Cu corrosion process.