In order to investigate the effects of processing pH stimulation on bioleaching of chalcopyrite by moderate thermophiles,copper leaching rates and the dynamics of microbial community structures of free and attached ce...In order to investigate the effects of processing pH stimulation on bioleaching of chalcopyrite by moderate thermophiles,copper leaching rates and the dynamics of microbial community structures of free and attached cells were monitored. The results indicated that when the processing pH values were respectively adjusted to 1.0 and 3.0 on day 14, both free and attached cells experienced an adaptive phase. Meanwhile, the copper leaching rates were 86.9% and 64.0%,respectively, as opposed to a copper leaching rate of 87.5% in the control group without pH stimulation. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis suggested that pH stimulation imposed less impact on the attached organisms than on the free cells, indicating that the attached cells were more resistant to processing pH stimulation than the free cells. Furthermore, adjusting processing pH to 3.0 significantly disrupted both free and attached microbial communities, and the bioleaching system could not recover to the normal status as the control group.展开更多
The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM)...The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM).The bacterial communities of free,attached,weakly-attached,and strongly-attached microbes in the later bioleaching stage were investigated.In AM group,the addition of lump sulphide ore resulted in the low leachate pH,high ferric iron concentration,and rapid microbial adsorption,which obtained the maximum copper extraction(60.1%)compared with LM(54.6%)and PM(43.9%)groups.The relative abundance of dominant genera and microbial communities of different microbiota underwent changes in three heap construction methods.The alpha-diversity indexes of attached,weakly-attached,and strongly-attached microbes were different,while no significant change was observed in free bacteria.The variation of whole bacterial community was significantly associated with solution pH,total iron,and ferric iron concentrations.Pearson correlation analysis and partial least square path model both indicated that attached bacteria made larger contribution to the copper extraction of tailings.展开更多
Microorganisms,one of the key factors affecting the bioleaching process,change the components of extracellular polymeric substance(EPS)and community structure to survive in leaching environments.In this work,Fourier t...Microorganisms,one of the key factors affecting the bioleaching process,change the components of extracellular polymeric substance(EPS)and community structure to survive in leaching environments.In this work,Fourier transform infrared(FTIR),X-ray powder diffraction(XRD)and 16S rDNA high-throughput sequence analyses were used to reveal the microbial changes in planktonic and sessile phases during bioleaching.The results showed the occupation of sessile cells decreased from 66.2%to(10±3)%.After bioleaching,the planktonic and sessile cells have similar EPS,but they are different from the original cells.Pyrite dissolution mainly occurs at the early and late stages with the decreasing of particle diameter,by 50%and 40%,respectively.The 16S rDNA gene based sequence analysis results in total of 1117420 Reads across the six samples,presented among 7 phyla,9 classes,17 orders,23 families and 31 genera.Genera Leptospirillum and Sulfobacillus are the main bacteria at the early and middle stages,and Leptospirillum is the main genus at the end of bioleaching.Aquabacterium and Acidovorax are special genera in sessile cells and Weissella is special in planktonic ones.展开更多
[Objective] This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucum-ber seedlings, and therefore to elucidate the microbial m...[Objective] This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucum-ber seedlings, and therefore to elucidate the microbial mechanism of grafting for in-creasing cucumber plants tolerance to Cu stress [Method] Four treatments： （1） un-grafted seedlings ＋ test soil （U0）; （2） ungrafted seedlings ＋ test soil ＋ CuSO4·5H2O （U1）; （3） grafted seedlings ＋ test soil （G0）; （4） grafted seedlings ＋ test soil ＋ Cu-SO4·5H2O （G1） were set in the pot culture experiment. The contents of free amino acids, organic acids, phenolic acid and sugars, microbial population and enzyme ac-tivity in the four treatment were measured, respectively. [Result] The secretion of amino acids and organic acids were increased under Cu stress. The amino acids secretions of grafted seedlings roots were obviously higher than ungrafted seedlings except for Phe and Val. At the same time, the secretion of oxalic acid, malic acid, acetic acid, citric acid, cinnamic acid, ρ-hydroxybenzoic acid and benzoic acid of grafted seedlings were significantly higher than ungrafted seedlings as wel . There-fore, more Cu2＋ were restricted in soil by chelating, complexing and precipitation with root exudates, and its toxicity was decreased. The soil microbial biomass C and N in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere, whereas basal respiration and metabolic quotient were signifi-cantly lower. Under Cu stress, the numbers of actinomyces and nitrogen fixing bac-teria decreased and the number of fungi increased significantly, whereas there was no significant difference in amounts of bacteria. The numbers of bacteria, actino-myces, and nitrogen fixing bacteria in grafted cucumber rhizosphere were significant-ly higher than those in ungrafted cucumber rhizosphere, but the number of fungi was opposite. The activities of soil urease, phosphatase, sucrase and catalase in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere. [Conclusion] These indicated that the soil microbial environment and soil enzymes activities were improved by grafting under Cu stress, and as a re-sult, the adaptability of cucumber to Cu stress was improved.展开更多
Meat and meat products are extremely perishable, so special care and handling must be exercised during slaughtering operation. Moreover, due to its high nutritive value, deterioration set in immediately after slaughte...Meat and meat products are extremely perishable, so special care and handling must be exercised during slaughtering operation. Moreover, due to its high nutritive value, deterioration set in immediately after slaughtered, therefore it is necessary to preserved meat, using simple techniques. One of such method of preservation is drying method to produced Intermediate Moisture Meat （IMM）. The quality attributes and microbiological status of Kundi, a West African dried meat product （IMM） were studied over three months of storage period by comparing commercial products and laboratory Kundi products. Chemical and minerals composition and microbiological counts were reported. Moisture and water activity results indicated that the experimental Kundi was sufficiently dried to minimize microbial growth. Fat oxidation levels measured by free fatty acids （FFA, %） on extracted fats were unacceptably high for the commercial Kundi （2.64%）, which may be a reflection of the oil used in spraying the products. Processing of Kundi, appears to have relative higher amounts of minerals than fresh meat but their relative solubility were lower. Aflatoxin levels far exceeded established safe limits for commercial samples while laboratory samples fell under the safe limits, resulting from the mould growth in each product, with laboratory samples having lower growth than commercial samples.展开更多
基金Project(31200382)supported by the National Natural Science Foundation of ChinaProject(2013FJ4068)supported by the Planned Science and Technology Project of Hunan Province,ChinaProject supported by Australia CSIRO OCE Science Leader Grant
文摘In order to investigate the effects of processing pH stimulation on bioleaching of chalcopyrite by moderate thermophiles,copper leaching rates and the dynamics of microbial community structures of free and attached cells were monitored. The results indicated that when the processing pH values were respectively adjusted to 1.0 and 3.0 on day 14, both free and attached cells experienced an adaptive phase. Meanwhile, the copper leaching rates were 86.9% and 64.0%,respectively, as opposed to a copper leaching rate of 87.5% in the control group without pH stimulation. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis suggested that pH stimulation imposed less impact on the attached organisms than on the free cells, indicating that the attached cells were more resistant to processing pH stimulation than the free cells. Furthermore, adjusting processing pH to 3.0 significantly disrupted both free and attached microbial communities, and the bioleaching system could not recover to the normal status as the control group.
基金financial supports from the National Key R&D Program of China(No.2018YFC1801804)the Shandong Provincial Natural Science Foundation,China(Nos.ZR2020QD120 and ZR2018LD001)Project of Introducing and Cultivating Young Talent in the Universities of Shandong Province,China(No.QC2019YY144)。
文摘The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM).The bacterial communities of free,attached,weakly-attached,and strongly-attached microbes in the later bioleaching stage were investigated.In AM group,the addition of lump sulphide ore resulted in the low leachate pH,high ferric iron concentration,and rapid microbial adsorption,which obtained the maximum copper extraction(60.1%)compared with LM(54.6%)and PM(43.9%)groups.The relative abundance of dominant genera and microbial communities of different microbiota underwent changes in three heap construction methods.The alpha-diversity indexes of attached,weakly-attached,and strongly-attached microbes were different,while no significant change was observed in free bacteria.The variation of whole bacterial community was significantly associated with solution pH,total iron,and ferric iron concentrations.Pearson correlation analysis and partial least square path model both indicated that attached bacteria made larger contribution to the copper extraction of tailings.
基金Project(U1608254)supported by the Special Fund for the National Natural Science Foundation of ChinaProjects(ZJKY2017(B)KFJJ01,ZJKY2017(B)KFJJ02)supported by the Zijin Mining Group Co.,Ltd.,China。
文摘Microorganisms,one of the key factors affecting the bioleaching process,change the components of extracellular polymeric substance(EPS)and community structure to survive in leaching environments.In this work,Fourier transform infrared(FTIR),X-ray powder diffraction(XRD)and 16S rDNA high-throughput sequence analyses were used to reveal the microbial changes in planktonic and sessile phases during bioleaching.The results showed the occupation of sessile cells decreased from 66.2%to(10±3)%.After bioleaching,the planktonic and sessile cells have similar EPS,but they are different from the original cells.Pyrite dissolution mainly occurs at the early and late stages with the decreasing of particle diameter,by 50%and 40%,respectively.The 16S rDNA gene based sequence analysis results in total of 1117420 Reads across the six samples,presented among 7 phyla,9 classes,17 orders,23 families and 31 genera.Genera Leptospirillum and Sulfobacillus are the main bacteria at the early and middle stages,and Leptospirillum is the main genus at the end of bioleaching.Aquabacterium and Acidovorax are special genera in sessile cells and Weissella is special in planktonic ones.
基金Supported by Shandong Modern Agricultural Technology & Industry System
文摘[Objective] This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucum-ber seedlings, and therefore to elucidate the microbial mechanism of grafting for in-creasing cucumber plants tolerance to Cu stress [Method] Four treatments： （1） un-grafted seedlings ＋ test soil （U0）; （2） ungrafted seedlings ＋ test soil ＋ CuSO4·5H2O （U1）; （3） grafted seedlings ＋ test soil （G0）; （4） grafted seedlings ＋ test soil ＋ Cu-SO4·5H2O （G1） were set in the pot culture experiment. The contents of free amino acids, organic acids, phenolic acid and sugars, microbial population and enzyme ac-tivity in the four treatment were measured, respectively. [Result] The secretion of amino acids and organic acids were increased under Cu stress. The amino acids secretions of grafted seedlings roots were obviously higher than ungrafted seedlings except for Phe and Val. At the same time, the secretion of oxalic acid, malic acid, acetic acid, citric acid, cinnamic acid, ρ-hydroxybenzoic acid and benzoic acid of grafted seedlings were significantly higher than ungrafted seedlings as wel . There-fore, more Cu2＋ were restricted in soil by chelating, complexing and precipitation with root exudates, and its toxicity was decreased. The soil microbial biomass C and N in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere, whereas basal respiration and metabolic quotient were signifi-cantly lower. Under Cu stress, the numbers of actinomyces and nitrogen fixing bac-teria decreased and the number of fungi increased significantly, whereas there was no significant difference in amounts of bacteria. The numbers of bacteria, actino-myces, and nitrogen fixing bacteria in grafted cucumber rhizosphere were significant-ly higher than those in ungrafted cucumber rhizosphere, but the number of fungi was opposite. The activities of soil urease, phosphatase, sucrase and catalase in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere. [Conclusion] These indicated that the soil microbial environment and soil enzymes activities were improved by grafting under Cu stress, and as a re-sult, the adaptability of cucumber to Cu stress was improved.
文摘Meat and meat products are extremely perishable, so special care and handling must be exercised during slaughtering operation. Moreover, due to its high nutritive value, deterioration set in immediately after slaughtered, therefore it is necessary to preserved meat, using simple techniques. One of such method of preservation is drying method to produced Intermediate Moisture Meat （IMM）. The quality attributes and microbiological status of Kundi, a West African dried meat product （IMM） were studied over three months of storage period by comparing commercial products and laboratory Kundi products. Chemical and minerals composition and microbiological counts were reported. Moisture and water activity results indicated that the experimental Kundi was sufficiently dried to minimize microbial growth. Fat oxidation levels measured by free fatty acids （FFA, %） on extracted fats were unacceptably high for the commercial Kundi （2.64%）, which may be a reflection of the oil used in spraying the products. Processing of Kundi, appears to have relative higher amounts of minerals than fresh meat but their relative solubility were lower. Aflatoxin levels far exceeded established safe limits for commercial samples while laboratory samples fell under the safe limits, resulting from the mould growth in each product, with laboratory samples having lower growth than commercial samples.
