Ethylthionocarbamates （ETC）, which is the most widely used as collectors in the flotation of sulfide, is known to cause serious pollution to soil and groundwater. The potential biodegradation of ETC was evaluated b...Ethylthionocarbamates （ETC）, which is the most widely used as collectors in the flotation of sulfide, is known to cause serious pollution to soil and groundwater. The potential biodegradation of ETC was evaluated by applying a mixed culture of iron-reducing bacteria （IRB） enriched from tailings dam sediments. The results showed that ETC can be degraded by IRB coupled to Fe（III） reduction, both of which can be increased in the presence of anthraquinone-2,6-disulfonate （AQDS）. Moreover, Fe（III）-EDTA was found to be a more favorable terminal electron acceptor compared to α-Fe2O3, e.g., within 30 d, 72% of ETC was degraded when α-Fe2O3＋AQDS was applied, while it is 82.67% when Fe（III）-EDTA＋AQDS is added. The dynamic models indicated that the kETC degradation was decreased in the order of Fe（III）-EDTA＋AQDS〉α-Fe2O3＋AQDS〉Fe（III）-EDTA〉α-Fe2O3, with the corresponding maximum biodegradation rates being 2.6, 2.45, 2.4 and 2.0 mg/（L·d）, respectively, and positive parallel correlations could be observed between kFe（III） and kETC. These findings demonstrate that IRB has a good application prospect in flotation wastewater.展开更多
Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not b...Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not be underestimated, the bulk of these processes can be ascribed to the specific activity of Iron-Reducing Bacteria (IRB). The reducing conditions of waterlogged lowland soils boost iron toxicity through the reduction of almost all iron into ferrous form (Fe2+), which can cause disorder in rice plant and crop yield losses. Aiming to contribute at the improvement of rice yield in Africa, an experiment was developed to evaluate the impact of subsurface drainage on IRB dynamics and activity during rice cultivation. Twelve concrete microplots with a clay-loam soil and a rice variety susceptible to iron toxicity (FKR 19) were used for the experiment. Soil in microplots was drained for 7 days (P1), 14 days (P2), and 21 days (P3), respectively. Control (T) microplots without drainage were prepared similarly. The evolution of IRB populations and the content of ferrous iron in the paddy soil and in soil near rice root were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. Data obtained were analyzed in relation to drainage frequency, rice growth stage, and rice yield using the Student t test and XLSTAT 7.5.2 statistical software. From the results obtained, the subsurface drainage reduced significantly IRB populations (p = 0.024). However, the drainage did not affect significantly ferrous iron concentration in the soil near rice roots (p = 0.708). The concentration of ferrous iron (p < 0.0001) in soil near rice roots and the number of IRB (p < 0.0001) were significantly higher during the rice tillering and maturity stages. Although no significant difference was observed for rice yield among treatments (p = 0.209), the P2 subsurface drainage showed the highest yield and the lowest concentration of ferrous iron in soil near rice roots.展开更多
Iron toxicity is a major stress to rice caused by a high concentration of reduced iron, in the soil in many lowlands worldwide. To reduce iron toxicity in the West African lowlands, an investigation was performed at t...Iron toxicity is a major stress to rice caused by a high concentration of reduced iron, in the soil in many lowlands worldwide. To reduce iron toxicity in the West African lowlands, an investigation was performed at the site of the University of Ouagadougou, in pots containing an iron toxic soil from the Kou Valley (West of Burkina Faso). The experiment objective was to study the effect of mineral fertilizer on Iron Reducing Bacteria (IRB) dynamics and activity during rice cultivation, iron accumulation in rice plant and rice biomass yield under iron toxicity conditions. BOUAKE-189 and ROK-5 rice varieties, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complex). Control pots without fertilization were prepared similarly. The kinetics of IRB 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 spectrometric method. Data obtained were analyzed in relation to fertilization mode, rice growth stage and rice yield using the student’s t-test and XLSTAT 2014 statistical software. The experiment revealed that NPK + Urea and NPK + Urea + Ca + Mg + Zn fertilization, decreased significantly (p < 0.0001) the number of IRB in the soil for BOUAKE-189 rice varieties. In most pots, highest IRB densities and ferrous iron content in soil were recorded from rice tillering and flowering to maturity stages, indicating that rice plants promoted microbial processes and iron reduction in soil. From the study, the NPK + Urea amendment decreased significantly ferrous iron content (p < 0.0001) in soil near BOUAKE-189 and ROK-5 rice varieties roots relatively to control pots. However, NPK + Urea + Ca + Zn + Mg amendment increased significantly ferrous iron content (p < 0.0001) in the soil near roots, Fe accumulation in plant biomass and rice yield for the two rice varieties.展开更多
Rivers are the primary contributors of iron and other elements to the global oceans.Iron-reducing bacteria play an important biogeochemical role in coupling the iron and carbon redox cycles.However,the extent of chang...Rivers are the primary contributors of iron and other elements to the global oceans.Iron-reducing bacteria play an important biogeochemical role in coupling the iron and carbon redox cycles.However,the extent of changes in community structures and iron-reduction activities of iron-reducing bacteria in riverine and coastal marine sediments remains unclear.This study presents information on the spatial patterns and relative abundance of iron-reducing bacteria in sediments of the Yellow River estuary and the adjacent Bohai Sea.High-throughput sequencing of bacterial 16S rRNA found that the highest relative abundances and diversities were from the estuary(Yellow River-Bohai Sea mixing zone).Pseudomonas,Thiobacillus,Geobacter,Rhodoferax,and Clostridium were the most abundant putative iron-reducing bacteria genera in the sediments of the Yellow River.Vibrio,Shewanella,and Thiobacillus were the most abundant in the sediments of the Bohai Sea.The putative iron-reducing bacterial community was positively correlated with the concentrations of total nitrogen and ammonium in coastal marine sediments,and was significantly correlated with the concentration of nitrate in river sediments.The riverine sediments,with a more diverse iron-reducing bacterial community,exhibited increased activity of Fe(III)reduction in enrichment cultures.The estuary-wide high abundance of putative iron-reducing bacteria suggests that the effect of river-sea interaction on bacterial distribution patterns is high.The results of this study will help the understanding of the biogeochemical cycling of iron in riverine and coastal marine environments.展开更多
Understanding the coupling relationships among lake physicochemical properties,internal nutrient recycling,and related microbes is key for the control of freshwater eutrophication.In this study,seasonal variations in ...Understanding the coupling relationships among lake physicochemical properties,internal nutrient recycling,and related microbes is key for the control of freshwater eutrophication.In this study,seasonal variations in microorganisms at the sediment–water interface(SWI)of the eutrophic Lake Chaohu in China were analyzed,in order to reveal changes in phosphorus(P)-cycling-related microbes in the sediments and its association with internal P release during the cyanobacterial life cycle.The identified P-cycling-related microbes include phosphorus-solubilizing bacteria(PSB)(dominant of Bacillus,Thiobacillus and Acinetobacter),sulfate-reducing bacteria(SRB)(dominant of Sva0081_sediment_group,norank_c__Thermodesulfovibrionia and Desulfatiglans)and iron-reducing bacteria(FeRB)(dominant of Geothermobacter,Anaeromyxobacter,Thermoanaerobaculum and Clostridium_sensu_stricto_1).Increased PSB and reduced proportions of iron-aluminum–bound P(Fe/Al-P)and calcium–bound P(Ca-P)from the benthic stage to initial cyanobacterial growth indicated that internal phosphorus was released through the solubilization of Fe/Al-P and Ca-P by PSB.Growth of cyanobacteria was accompanied by cyanobacteria death,deposition,and degradation during early algal blooms,which increased SRB caused by high organic matter and the net deposition of phosphorus in the western lake.Conversely,phosphorus release in eastern lake was observed because of organic phosphorus mineralization.High linear discriminant analysis effect size of SRB and FeRB and the decreased Fe/Al-P in sediments indicated sulfide-mediated chemical iron reduction(SCIR)and FeRB-mediated microbial iron reduction mechanisms for internal phosphorus release during late algal blooms.The observed seasonal pattern of P-cycling-related microbes and its mediation on internal phosphorus release provides a foundation for internal P management in Lake Chaohu.展开更多
基金Project(51708561)supported by the National Natural Science Foundation of ChinaProjects(CZP17097,CZW15037)supported by the Fundamental Research Funds for the Central Universities,China
文摘Ethylthionocarbamates （ETC）, which is the most widely used as collectors in the flotation of sulfide, is known to cause serious pollution to soil and groundwater. The potential biodegradation of ETC was evaluated by applying a mixed culture of iron-reducing bacteria （IRB） enriched from tailings dam sediments. The results showed that ETC can be degraded by IRB coupled to Fe（III） reduction, both of which can be increased in the presence of anthraquinone-2,6-disulfonate （AQDS）. Moreover, Fe（III）-EDTA was found to be a more favorable terminal electron acceptor compared to α-Fe2O3, e.g., within 30 d, 72% of ETC was degraded when α-Fe2O3＋AQDS was applied, while it is 82.67% when Fe（III）-EDTA＋AQDS is added. The dynamic models indicated that the kETC degradation was decreased in the order of Fe（III）-EDTA＋AQDS〉α-Fe2O3＋AQDS〉Fe（III）-EDTA〉α-Fe2O3, with the corresponding maximum biodegradation rates being 2.6, 2.45, 2.4 and 2.0 mg/（L·d）, respectively, and positive parallel correlations could be observed between kFe（III） and kETC. These findings demonstrate that IRB has a good application prospect in flotation wastewater.
文摘Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not be underestimated, the bulk of these processes can be ascribed to the specific activity of Iron-Reducing Bacteria (IRB). The reducing conditions of waterlogged lowland soils boost iron toxicity through the reduction of almost all iron into ferrous form (Fe2+), which can cause disorder in rice plant and crop yield losses. Aiming to contribute at the improvement of rice yield in Africa, an experiment was developed to evaluate the impact of subsurface drainage on IRB dynamics and activity during rice cultivation. Twelve concrete microplots with a clay-loam soil and a rice variety susceptible to iron toxicity (FKR 19) were used for the experiment. Soil in microplots was drained for 7 days (P1), 14 days (P2), and 21 days (P3), respectively. Control (T) microplots without drainage were prepared similarly. The evolution of IRB populations and the content of ferrous iron in the paddy soil and in soil near rice root were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. Data obtained were analyzed in relation to drainage frequency, rice growth stage, and rice yield using the Student t test and XLSTAT 7.5.2 statistical software. From the results obtained, the subsurface drainage reduced significantly IRB populations (p = 0.024). However, the drainage did not affect significantly ferrous iron concentration in the soil near rice roots (p = 0.708). The concentration of ferrous iron (p < 0.0001) in soil near rice roots and the number of IRB (p < 0.0001) were significantly higher during the rice tillering and maturity stages. Although no significant difference was observed for rice yield among treatments (p = 0.209), the P2 subsurface drainage showed the highest yield and the lowest concentration of ferrous iron in soil near rice roots.
文摘Iron toxicity is a major stress to rice caused by a high concentration of reduced iron, in the soil in many lowlands worldwide. To reduce iron toxicity in the West African lowlands, an investigation was performed at the site of the University of Ouagadougou, in pots containing an iron toxic soil from the Kou Valley (West of Burkina Faso). The experiment objective was to study the effect of mineral fertilizer on Iron Reducing Bacteria (IRB) dynamics and activity during rice cultivation, iron accumulation in rice plant and rice biomass yield under iron toxicity conditions. BOUAKE-189 and ROK-5 rice varieties, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complex). Control pots without fertilization were prepared similarly. The kinetics of IRB 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 spectrometric method. Data obtained were analyzed in relation to fertilization mode, rice growth stage and rice yield using the student’s t-test and XLSTAT 2014 statistical software. The experiment revealed that NPK + Urea and NPK + Urea + Ca + Mg + Zn fertilization, decreased significantly (p < 0.0001) the number of IRB in the soil for BOUAKE-189 rice varieties. In most pots, highest IRB densities and ferrous iron content in soil were recorded from rice tillering and flowering to maturity stages, indicating that rice plants promoted microbial processes and iron reduction in soil. From the study, the NPK + Urea amendment decreased significantly ferrous iron content (p < 0.0001) in soil near BOUAKE-189 and ROK-5 rice varieties roots relatively to control pots. However, NPK + Urea + Ca + Zn + Mg amendment increased significantly ferrous iron content (p < 0.0001) in the soil near roots, Fe accumulation in plant biomass and rice yield for the two rice varieties.
基金the National Natural Science Foundation of China(nos.91751112.41807325,and 41573071)the senior user project of RV KEXUE(no.KEXUE2018G01)+2 种基金the Key Research Project of Frontier Science(no.QYZDJ-SSW-DQC015)of Chinese Academy of Sciencesthe Natural Science Foundation(no.JQ201608 and ZR2O18MDOI1)the Young Taishan Scholars Program(no.tsqn20161054)of Shandong Province.
文摘Rivers are the primary contributors of iron and other elements to the global oceans.Iron-reducing bacteria play an important biogeochemical role in coupling the iron and carbon redox cycles.However,the extent of changes in community structures and iron-reduction activities of iron-reducing bacteria in riverine and coastal marine sediments remains unclear.This study presents information on the spatial patterns and relative abundance of iron-reducing bacteria in sediments of the Yellow River estuary and the adjacent Bohai Sea.High-throughput sequencing of bacterial 16S rRNA found that the highest relative abundances and diversities were from the estuary(Yellow River-Bohai Sea mixing zone).Pseudomonas,Thiobacillus,Geobacter,Rhodoferax,and Clostridium were the most abundant putative iron-reducing bacteria genera in the sediments of the Yellow River.Vibrio,Shewanella,and Thiobacillus were the most abundant in the sediments of the Bohai Sea.The putative iron-reducing bacterial community was positively correlated with the concentrations of total nitrogen and ammonium in coastal marine sediments,and was significantly correlated with the concentration of nitrate in river sediments.The riverine sediments,with a more diverse iron-reducing bacterial community,exhibited increased activity of Fe(III)reduction in enrichment cultures.The estuary-wide high abundance of putative iron-reducing bacteria suggests that the effect of river-sea interaction on bacterial distribution patterns is high.The results of this study will help the understanding of the biogeochemical cycling of iron in riverine and coastal marine environments.
基金supported by the National Natural Science Foundation of China(No.U22A20616).
文摘Understanding the coupling relationships among lake physicochemical properties,internal nutrient recycling,and related microbes is key for the control of freshwater eutrophication.In this study,seasonal variations in microorganisms at the sediment–water interface(SWI)of the eutrophic Lake Chaohu in China were analyzed,in order to reveal changes in phosphorus(P)-cycling-related microbes in the sediments and its association with internal P release during the cyanobacterial life cycle.The identified P-cycling-related microbes include phosphorus-solubilizing bacteria(PSB)(dominant of Bacillus,Thiobacillus and Acinetobacter),sulfate-reducing bacteria(SRB)(dominant of Sva0081_sediment_group,norank_c__Thermodesulfovibrionia and Desulfatiglans)and iron-reducing bacteria(FeRB)(dominant of Geothermobacter,Anaeromyxobacter,Thermoanaerobaculum and Clostridium_sensu_stricto_1).Increased PSB and reduced proportions of iron-aluminum–bound P(Fe/Al-P)and calcium–bound P(Ca-P)from the benthic stage to initial cyanobacterial growth indicated that internal phosphorus was released through the solubilization of Fe/Al-P and Ca-P by PSB.Growth of cyanobacteria was accompanied by cyanobacteria death,deposition,and degradation during early algal blooms,which increased SRB caused by high organic matter and the net deposition of phosphorus in the western lake.Conversely,phosphorus release in eastern lake was observed because of organic phosphorus mineralization.High linear discriminant analysis effect size of SRB and FeRB and the decreased Fe/Al-P in sediments indicated sulfide-mediated chemical iron reduction(SCIR)and FeRB-mediated microbial iron reduction mechanisms for internal phosphorus release during late algal blooms.The observed seasonal pattern of P-cycling-related microbes and its mediation on internal phosphorus release provides a foundation for internal P management in Lake Chaohu.
