目的对六价铬[Cr（VI）]还原菌Cr4-1进行鉴定,并给出细菌生长和Cr（VI）还原的较好条件。方法采用生理生化法和16s r DNA测序法,对细菌Cr4-1进行鉴定,并分别研究温度、p H、初始Cr（VI）浓度和摇床转速对细菌生长和Cr（VI）还原效果的影...目的对六价铬[Cr（VI）]还原菌Cr4-1进行鉴定,并给出细菌生长和Cr（VI）还原的较好条件。方法采用生理生化法和16s r DNA测序法,对细菌Cr4-1进行鉴定,并分别研究温度、p H、初始Cr（VI）浓度和摇床转速对细菌生长和Cr（VI）还原效果的影响,用质量平衡法分析还原反应终产物。结果从驯化后的活性污泥中筛选的Cr（VI）还原菌Cr4-1,经鉴定为蜡样芽孢杆菌。细菌生长的较好条件为：25℃,p H 7-8,摇床转速200 r/min;还原Cr（VI）的适宜温度为35℃,p H8-9。Cr（VI）初始浓度从20 mg/L增加至60 mg/L,还原效果呈下降趋势。在较好的还原条件下,Cr（VI）初始浓度为30 mg/L时,9 h的还原率可达100%,还原反应终产物为可溶性三价铬。结论细菌Cr4-1为高效Cr（VI）还原菌,还原终产物为可溶性三价铬。展开更多
基于16S r DNA V6~V8可变区的聚合酶链式反应-变性梯度凝胶电泳(polymerase chain reaction-denaturing gradient gel electrophoresis,PCR-DGGE)技术分析肉鸡屠宰加工过程中减菌处理前后胴体或产品细菌多样性。在预冷环节前采用50℃、1...基于16S r DNA V6~V8可变区的聚合酶链式反应-变性梯度凝胶电泳(polymerase chain reaction-denaturing gradient gel electrophoresis,PCR-DGGE)技术分析肉鸡屠宰加工过程中减菌处理前后胴体或产品细菌多样性。在预冷环节前采用50℃、1.5%乳酸溶液对肉鸡胴体冲淋15 s进行减菌处理,采集屠宰加工环节中减菌处理前后的胴体或分割产品表面样品,提取样品中的细菌总DNA,通过16S r DNA V6~V8可变区的PCR扩增,变性梯度凝胶电泳,对PCR扩增片段割胶回收、克隆测序分析减菌前后细菌菌相变化。结果表明,减菌前,胴体清洗环节DGGE条带的数量最多、亮度最强,细菌污染最严重,其次是分割环节,而预冷环节细菌种类及数量最少,污染程度最低;减菌后,各屠宰加工环节细菌种类与数量较减菌前均有所减少,其中胴体清洗环节与分割环节细菌的种类与数量减少量最多,预冷环节细菌的种类及数量最少,不同屠宰加工环节细菌种类并不完全一致;乳杆菌属细菌在整个肉鸡屠宰加工过程中均有出现,与肠杆菌科和假单胞菌属细菌为肉鸡屠宰加工过程中的优势腐败菌。展开更多
The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%～4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhib...The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%～4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhibition technique is employed to evaluate the rates of nitrification, denitrification and nitrate reduction by bacterial activities in the sediments at three sites. The average of nitrification, denitrification and nitrate reduction rates ranges from 0.32 to 2.43, 0.03 to 0.84 and 4.17 to 13.06 mmol/(m2·h), respectively. The ver- tical profiles of the sediments show that the nitrification and denitrification processes mainly take place in the depth from 0 to 4 cm and depend on regional conditions. The rates of nitrification, denitrification and nitrate reduction are dominated by Eh, nitrate and ammoni- um concentrations in sediments and DO in overlay water. There is a coupling between nitrification and denitrification.展开更多
Silver nanoparticle （SNP） is a threat to soil, water and human health. Protection of environment from silver nanoparticles is a major concern. A sewage isolate, Bacillus pumilus treated with SNPs showed similar grow...Silver nanoparticle （SNP） is a threat to soil, water and human health. Protection of environment from silver nanoparticles is a major concern. A sewage isolate, Bacillus pumilus treated with SNPs showed similar growth kinetics to that without nanoparticles. A reduction in the amount of exopolysaccharides was observed after SNPs - B. pumilus culture supernatant interaction. The Fourier transform infrared spectroscopy （FT-IR） peaks for the exopolysaccharides extracted from the bacterial culture supernatant and＇the interacted SNPs were almost similar. The exopolysaccharide capping of the SNPs was confirmed by UV-Visible, FT-IR and X-ray diffraction analysis. The study of bacterial exopolysaccharides capped SNPs with E. coli, S. aureus and M. luteus showed less toxicity compared to uncoated SNPs. Our studies suggested that the capping of nanopartieles by bacterially produced exopolysaccharides serve as the probable mechanism of tolerance.展开更多
The lacustrine organic-rich shale in the Permian Lucaogou(LCG)Formation of the Jimsar Sag,Junggar Basin,is one of the main shale oil plays in China.In this paper,geological and geochemical research techniques were emp...The lacustrine organic-rich shale in the Permian Lucaogou(LCG)Formation of the Jimsar Sag,Junggar Basin,is one of the main shale oil plays in China.In this paper,geological and geochemical research techniques were employed to evaluate the geochemical variability of the lacustrine shale and the pro-duction of organic matter and its preservation conditions.The LcG Formation is characterized by its complex mineral compositions and a wide range of organic matter richness and quality.The presence of high proportions ofβ-carotane and C2g steranes,indicates that the organic matter mainly originated from phytoplankton and aquatic algal-bacterial organisms,especially cyanobacteria.This study found that the productivity of the Lower LCG Member(P2li)was highest,and the Middle LCG Member(P_(2)l_(2))was the lowest.During the deposition of the Lower LCG Member,the lake's bottom water was predominantly a reducing environment,and the degradation of organic matter was largely a result of bacterial sulfate reduction.During the deposition of the Middle and Upper LCG members,the lake's bottom water was mainly oxidizing,and the degradation of organic matter was likely to be caused by aerobic processes.Based on a comprehensive analysis of the origin and production of organic matter,as well as its depo-sitional environment and preservation conditions,two organic matter accumulation models were pro-posed to explain the distribution of the organic-rich shale.In model A,the high influx of volcanic ash released nutrients and brought abundant sulfate into the water,the accumulation of organic matter was mainly controlled by the preservation of organic matter,which was mainly controlled by BsR.In the model B,the influx of volcanic ash was small,organic matter was mainly degraded by oxygen and the accumulation of organic matter is mainly determined by the production of organic matter.展开更多
Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial co...Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial community to the increased NB contents. In this study, a laboratory-scale expanded granular sludge bed reactor was operated continuously to treat high-sulfate organic wastewater with increased NB contents. Results successfully demonstrated that the presence of more than 50 mg/L NB depressed sulfate reduction and such inhibition was partly reversible. Bath experiments showed that the maximum specific desulfuration activity (SDA) decreased from 135.80 mg SO4^2-/gVSS/d to 30.78 mg SO4^2-/gVSS/d when the NB contents increased from none to 400 mg/L. High-throughput sequencing showed that NB also greatly affected bacterial community structure. Bcicteroidetes dominated in the bioreactor. The abundance of Proteobacteria increased with NB addition while Firmicutes presented an opposite trend. Proteobacteria gradually replaced Finnicutes for the dominance in response to the increase of influent NB concentrations.The genus Desulfovibrio was the dominant sulfate-reducing bacteria (SRB) with absence or presence of NB, but was inhibited under high content of NB. The results provided better understanding for the biological sulfate reduction under NB stress.展开更多
The decentralized production of H_(2)O_(2) via a twoelectron oxygen reduction reaction(2e^(-)ORR)has emerged as a promising alternative to the energy-intensive anthraquinone(AQ)process.However,its practical applicatio...The decentralized production of H_(2)O_(2) via a twoelectron oxygen reduction reaction(2e^(-)ORR)has emerged as a promising alternative to the energy-intensive anthraquinone(AQ)process.However,its practical application requires 2eORR electrocatalysts with high activity and selectivity.Herein,we report the synthesis of metallic Ni nanoparticles anchored on bacterial cellulose-derived carbon fibers(Ni-NPs/BCCF)via a facile impregnation-pyrolysis method as efficient electrocatalysts for 2 e-ORR to H_(2)O_(2).By tuning the amount of Ni precursor,the best electrocatalytic performance toward 2 eORR was achieved for Ni-NPs/BCCF-20.7,affording a high H_(2)O_(2) selectivity of ~90% and an onset potential of 0.75 V vs.reversible hydrogen electrode(RHE)in an alkaline electrolyte.Ni-NPs/BCCF-20.7 achieved the largest H_(2)O_(2) yield rate of 162.7±13.7 mmol gcat^(-1)h^(-1) and the highest Faradaic efficiency of 93.9%±4.2% at 0.2 and 0.5 V vs.RHE from the bulk ORR system,respectively.Theoretical calculations revealed the more favorable"end-on"adsorption configuration of molecular oxygen on the exposed Ni(111)plane,which can effectively suppress the O-O bond dissociation,resulting in high selectivity for H_(2)O_(2) generation.展开更多
Inspired by the foraging behavior of E.coli bacteria,bacterial foraging optimization(BFO)has emerged as a powerful technique for solving optimization problems.However,BFO shows poor performance on complex and high-dim...Inspired by the foraging behavior of E.coli bacteria,bacterial foraging optimization(BFO)has emerged as a powerful technique for solving optimization problems.However,BFO shows poor performance on complex and high-dimensional optimization problems.In order to improve the performance of BFO,a new dynamic bacterial foraging optimization based on clonal selection(DBFO-CS)is proposed.Instead of fixed step size in the chemotaxis operator,a new piecewise strategy adjusts the step size dynamically by regulatory factor in order to balance between exploration and exploitation during optimization process,which can improve convergence speed.Furthermore,reproduction operator based on clonal selection can add excellent genes to bacterial populations in order to improve bacterial natural selection and help good individuals to be protected,which can enhance convergence precision.Then,a set of benchmark functions have been used to test the proposed algorithm.The results show that DBFO-CS offers significant improvements than BFO on convergence,accuracy and robustness.A complex optimization problem of model reduction on stable and unstable linear systems based on DBFO-CS is presented.Results show that the proposed algorithm can efficiently approximate the systems.展开更多
文摘基于16S r DNA V6~V8可变区的聚合酶链式反应-变性梯度凝胶电泳(polymerase chain reaction-denaturing gradient gel electrophoresis,PCR-DGGE)技术分析肉鸡屠宰加工过程中减菌处理前后胴体或产品细菌多样性。在预冷环节前采用50℃、1.5%乳酸溶液对肉鸡胴体冲淋15 s进行减菌处理,采集屠宰加工环节中减菌处理前后的胴体或分割产品表面样品,提取样品中的细菌总DNA,通过16S r DNA V6~V8可变区的PCR扩增,变性梯度凝胶电泳,对PCR扩增片段割胶回收、克隆测序分析减菌前后细菌菌相变化。结果表明,减菌前,胴体清洗环节DGGE条带的数量最多、亮度最强,细菌污染最严重,其次是分割环节,而预冷环节细菌种类及数量最少,污染程度最低;减菌后,各屠宰加工环节细菌种类与数量较减菌前均有所减少,其中胴体清洗环节与分割环节细菌的种类与数量减少量最多,预冷环节细菌的种类及数量最少,不同屠宰加工环节细菌种类并不完全一致;乳杆菌属细菌在整个肉鸡屠宰加工过程中均有出现,与肠杆菌科和假单胞菌属细菌为肉鸡屠宰加工过程中的优势腐败菌。
基金supported by the Knowledge Innovation Engineering of Chinese Academy of Sciences under contract No.KZCX3-SW-214,KSCX2-SW-132the Natural Science Foundation of Guangdong Province under contract No.032622.
文摘The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%～4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhibition technique is employed to evaluate the rates of nitrification, denitrification and nitrate reduction by bacterial activities in the sediments at three sites. The average of nitrification, denitrification and nitrate reduction rates ranges from 0.32 to 2.43, 0.03 to 0.84 and 4.17 to 13.06 mmol/(m2·h), respectively. The ver- tical profiles of the sediments show that the nitrification and denitrification processes mainly take place in the depth from 0 to 4 cm and depend on regional conditions. The rates of nitrification, denitrification and nitrate reduction are dominated by Eh, nitrate and ammoni- um concentrations in sediments and DO in overlay water. There is a coupling between nitrification and denitrification.
基金VIT University Chancellor for providing us with funding to carry out our research
文摘Silver nanoparticle （SNP） is a threat to soil, water and human health. Protection of environment from silver nanoparticles is a major concern. A sewage isolate, Bacillus pumilus treated with SNPs showed similar growth kinetics to that without nanoparticles. A reduction in the amount of exopolysaccharides was observed after SNPs - B. pumilus culture supernatant interaction. The Fourier transform infrared spectroscopy （FT-IR） peaks for the exopolysaccharides extracted from the bacterial culture supernatant and＇the interacted SNPs were almost similar. The exopolysaccharide capping of the SNPs was confirmed by UV-Visible, FT-IR and X-ray diffraction analysis. The study of bacterial exopolysaccharides capped SNPs with E. coli, S. aureus and M. luteus showed less toxicity compared to uncoated SNPs. Our studies suggested that the capping of nanopartieles by bacterially produced exopolysaccharides serve as the probable mechanism of tolerance.
基金supported by National Science Foundation for Young Scientists of China(Grant 41702143)Major basic science and technology projects of CNPC(2021DJ0206-03)。
文摘The lacustrine organic-rich shale in the Permian Lucaogou(LCG)Formation of the Jimsar Sag,Junggar Basin,is one of the main shale oil plays in China.In this paper,geological and geochemical research techniques were employed to evaluate the geochemical variability of the lacustrine shale and the pro-duction of organic matter and its preservation conditions.The LcG Formation is characterized by its complex mineral compositions and a wide range of organic matter richness and quality.The presence of high proportions ofβ-carotane and C2g steranes,indicates that the organic matter mainly originated from phytoplankton and aquatic algal-bacterial organisms,especially cyanobacteria.This study found that the productivity of the Lower LCG Member(P2li)was highest,and the Middle LCG Member(P_(2)l_(2))was the lowest.During the deposition of the Lower LCG Member,the lake's bottom water was predominantly a reducing environment,and the degradation of organic matter was largely a result of bacterial sulfate reduction.During the deposition of the Middle and Upper LCG members,the lake's bottom water was mainly oxidizing,and the degradation of organic matter was likely to be caused by aerobic processes.Based on a comprehensive analysis of the origin and production of organic matter,as well as its depo-sitional environment and preservation conditions,two organic matter accumulation models were pro-posed to explain the distribution of the organic-rich shale.In model A,the high influx of volcanic ash released nutrients and brought abundant sulfate into the water,the accumulation of organic matter was mainly controlled by the preservation of organic matter,which was mainly controlled by BsR.In the model B,the influx of volcanic ash was small,organic matter was mainly degraded by oxygen and the accumulation of organic matter is mainly determined by the production of organic matter.
基金the National Natural Science Foundation of China (Grant Nos. 51378251 and 51408298)National Key R&D Program of China (No. 2016YFE0112300).
文摘Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial community to the increased NB contents. In this study, a laboratory-scale expanded granular sludge bed reactor was operated continuously to treat high-sulfate organic wastewater with increased NB contents. Results successfully demonstrated that the presence of more than 50 mg/L NB depressed sulfate reduction and such inhibition was partly reversible. Bath experiments showed that the maximum specific desulfuration activity (SDA) decreased from 135.80 mg SO4^2-/gVSS/d to 30.78 mg SO4^2-/gVSS/d when the NB contents increased from none to 400 mg/L. High-throughput sequencing showed that NB also greatly affected bacterial community structure. Bcicteroidetes dominated in the bioreactor. The abundance of Proteobacteria increased with NB addition while Firmicutes presented an opposite trend. Proteobacteria gradually replaced Finnicutes for the dominance in response to the increase of influent NB concentrations.The genus Desulfovibrio was the dominant sulfate-reducing bacteria (SRB) with absence or presence of NB, but was inhibited under high content of NB. The results provided better understanding for the biological sulfate reduction under NB stress.
基金financially supported by the National Natural Science Foundation of China(51872292)China Postdoctoral Science Foundation(E04BFGCV)the CASHIPS Director’s Fund(YZJJ2021QN18)。
文摘The decentralized production of H_(2)O_(2) via a twoelectron oxygen reduction reaction(2e^(-)ORR)has emerged as a promising alternative to the energy-intensive anthraquinone(AQ)process.However,its practical application requires 2eORR electrocatalysts with high activity and selectivity.Herein,we report the synthesis of metallic Ni nanoparticles anchored on bacterial cellulose-derived carbon fibers(Ni-NPs/BCCF)via a facile impregnation-pyrolysis method as efficient electrocatalysts for 2 e-ORR to H_(2)O_(2).By tuning the amount of Ni precursor,the best electrocatalytic performance toward 2 eORR was achieved for Ni-NPs/BCCF-20.7,affording a high H_(2)O_(2) selectivity of ~90% and an onset potential of 0.75 V vs.reversible hydrogen electrode(RHE)in an alkaline electrolyte.Ni-NPs/BCCF-20.7 achieved the largest H_(2)O_(2) yield rate of 162.7±13.7 mmol gcat^(-1)h^(-1) and the highest Faradaic efficiency of 93.9%±4.2% at 0.2 and 0.5 V vs.RHE from the bulk ORR system,respectively.Theoretical calculations revealed the more favorable"end-on"adsorption configuration of molecular oxygen on the exposed Ni(111)plane,which can effectively suppress the O-O bond dissociation,resulting in high selectivity for H_(2)O_(2) generation.
基金This work is supported in part by National Natural Science Foundation of China under Grant no.51375368.
文摘Inspired by the foraging behavior of E.coli bacteria,bacterial foraging optimization(BFO)has emerged as a powerful technique for solving optimization problems.However,BFO shows poor performance on complex and high-dimensional optimization problems.In order to improve the performance of BFO,a new dynamic bacterial foraging optimization based on clonal selection(DBFO-CS)is proposed.Instead of fixed step size in the chemotaxis operator,a new piecewise strategy adjusts the step size dynamically by regulatory factor in order to balance between exploration and exploitation during optimization process,which can improve convergence speed.Furthermore,reproduction operator based on clonal selection can add excellent genes to bacterial populations in order to improve bacterial natural selection and help good individuals to be protected,which can enhance convergence precision.Then,a set of benchmark functions have been used to test the proposed algorithm.The results show that DBFO-CS offers significant improvements than BFO on convergence,accuracy and robustness.A complex optimization problem of model reduction on stable and unstable linear systems based on DBFO-CS is presented.Results show that the proposed algorithm can efficiently approximate the systems.
