1,2-Dichloroethane (DCA), a potential mutagen and carcinogen, is commonly introduced into the environment through its industrial and agricultural use. In this study, the impact of lead and mercury on DCA degradation...1,2-Dichloroethane (DCA), a potential mutagen and carcinogen, is commonly introduced into the environment through its industrial and agricultural use. In this study, the impact of lead and mercury on DCA degradation in soil was investigated, owing to the complex co-contamination problem frequently encountered in most sites. 1,2-Dichloroethane was degraded readily in both contaminated loam and clay soils with the degradation rate constants ranging between 0.370-0.536 week-1 and 0.309-0.417 week-1, respectively. The presence of heavy metals have a negative impact on DCA degradation in both soil types, resulting in up to 24.11% reduction in DCA degradation within one week. Both biostimulation and treatment additives increased DCA degradation, with the best degradation observed upon addition of glucose and a combination of diphosphate salt and sodium chloride, leading to about 17.91% and 43.50% increase in DCA degradation, respectively. The results have promising potential for effective remediation of soils co-contaminated with chlorinated organics and heavy metals. However, the best bioremediation strategy will depend on the soil types, microbial population present in the soil matrices, nutrients availability and metal forms.展开更多
The innate toxicity of dichloroethenes(DCEs) and their tendency to be reduced to vinyl chloride(VC)(a known human carcinogen) is a cause for environmental concern. Aerobic bacteria capable of growth on cis- and tran...The innate toxicity of dichloroethenes(DCEs) and their tendency to be reduced to vinyl chloride(VC)(a known human carcinogen) is a cause for environmental concern. Aerobic bacteria capable of growth on cis- and trans-DCEs as sole carbon and energy sources were isolated by enrichment culture technique and identified to belong to the genera; Bacillus, Pseudomonas and Acinetobacter. Axenic and mixed cultures of the bacterial isolates utilized DCEs at concentrations above the maximum contaminant level allowable in drinking water by the Environmental Protection Agency. Their specific growth rate constant ranged significantly(P<0.05) between 0.346—0.552 and 0.461—0.667 d -1; while the maximum specific substrate utilization rate ranged significantly(P<0.05) between 20.01—29.79 and 31.40—42.83 nmol h -1 (mg of protein) -1 in cis- and trans-DCE, respectively. The optimum growth was observed at 30℃ and at a pH of 7.0 with up to 96% of the stoichiometric-expected chloride released. Serial adaptation positively affected the growth yields and dehalogenase activities of the organisms with multiple antibiotic patterns also demonstrated by the isolates. These findings therefore indicated the important roles that these organisms may play in the bioremediation of sites polluted with chlorinated ethene compounds in Africa.展开更多
The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived f...The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived from the hybrid progenies of Wujing 13 and Milky Princess(Kantou 194)with polymorphism in soluble starch synthase gene SSIIa(SSII-3)and SSIIIa(SSIII-2)but no polymorphism in other starch synthase related genes were used as test materials.The genotypes of SSIIa and SSIIIa allele were identified by molecular markers,and the allelic effects of SSIIa and SSIIIa gene on amylose content(AC),gel consistency(GC),gelatinization temperature(GT)and rapid visco analyzer(RVA)profile characteristics were analyzed.The significant effects of SSIIa and SSIIIa alleles and the interactive effects between two genes on AC,GT,GC and RVA profile characteristics were found.The SSIIa and SSIIIa alleles from Wujing13 shown positive effects on AC with an average increase of 1.87 and 1.23%in 2 years respectively.There was no significant effect on GT for SSIIa or SSIIIa allele but remarkable influence on GT when the co-existence of the two genes.The genotype SSIIa^(mp)SSIIIa^(mp) shown 1.34℃higher GT than genotype SSIIawjSSIIIawj(mp and wj indicated that the gene was derived from Milky Princess and Wujing 13 respectively,the same as in the below).Different genes and alleles resulted in significant different GC.The genetic effect of SSIIawj and SSIIIamp on GC was 8.74 and 9.62mm respectively.The GC of SSIIa^(wj)SSIIIa^(mp) was 10.64 and 16.95mm higher than that of SSIIa^(mp)SSIIIa^(wj) and SSIIawjSSIIIawj,respectively.The allele SSIIa^(wj) could increase the peak viscosity(PKV),hot paste viscosity(HPV),cool paste viscosity(CPV)and breakdown viscosity(BDV),while decrease the consistency viscosity(CSV)and setback viscosity(SBV).However for the allele SSIIIa^(wj) the opposite was true.The genotype SSIIa^(wj)SSIIIa^(mp) had the largest PKV,HPV and CPV,the genotype SSIIa^(wj)SSIIIa^(wj) had the largest BDV and CSV,but the genotype SSIIa^(wj)SSIIIa^(mp) had the least SBV.According to the comprehensive effect of each trait,the genotype SSIIawjSSIIIamp was the best.The allelic variation and interaction effect of SSIIa and SSIIIa genes have important reference value for improving cooking and eating quality of semi waxy japonica rice.展开更多
基金supported by the Competitive Research Grant of the University of KwaZulu-Natal, Durbanthe National Research Foundation of South Africa.
文摘1,2-Dichloroethane (DCA), a potential mutagen and carcinogen, is commonly introduced into the environment through its industrial and agricultural use. In this study, the impact of lead and mercury on DCA degradation in soil was investigated, owing to the complex co-contamination problem frequently encountered in most sites. 1,2-Dichloroethane was degraded readily in both contaminated loam and clay soils with the degradation rate constants ranging between 0.370-0.536 week-1 and 0.309-0.417 week-1, respectively. The presence of heavy metals have a negative impact on DCA degradation in both soil types, resulting in up to 24.11% reduction in DCA degradation within one week. Both biostimulation and treatment additives increased DCA degradation, with the best degradation observed upon addition of glucose and a combination of diphosphate salt and sodium chloride, leading to about 17.91% and 43.50% increase in DCA degradation, respectively. The results have promising potential for effective remediation of soils co-contaminated with chlorinated organics and heavy metals. However, the best bioremediation strategy will depend on the soil types, microbial population present in the soil matrices, nutrients availability and metal forms.
文摘The innate toxicity of dichloroethenes(DCEs) and their tendency to be reduced to vinyl chloride(VC)(a known human carcinogen) is a cause for environmental concern. Aerobic bacteria capable of growth on cis- and trans-DCEs as sole carbon and energy sources were isolated by enrichment culture technique and identified to belong to the genera; Bacillus, Pseudomonas and Acinetobacter. Axenic and mixed cultures of the bacterial isolates utilized DCEs at concentrations above the maximum contaminant level allowable in drinking water by the Environmental Protection Agency. Their specific growth rate constant ranged significantly(P<0.05) between 0.346—0.552 and 0.461—0.667 d -1; while the maximum specific substrate utilization rate ranged significantly(P<0.05) between 20.01—29.79 and 31.40—42.83 nmol h -1 (mg of protein) -1 in cis- and trans-DCE, respectively. The optimum growth was observed at 30℃ and at a pH of 7.0 with up to 96% of the stoichiometric-expected chloride released. Serial adaptation positively affected the growth yields and dehalogenase activities of the organisms with multiple antibiotic patterns also demonstrated by the isolates. These findings therefore indicated the important roles that these organisms may play in the bioremediation of sites polluted with chlorinated ethene compounds in Africa.
基金supported by Jiangsu Natural Science Foundation(No.BK20180302)Jiangsu agricultural science and Technology Innovation Fund(No.CX[18]1001)+3 种基金Jiangsu Key Research and development program(No.BE2018357)Jiangsu major new varieties creation project(No.PZCZ201703)the earmarked fund for China Agriculture Research System(No.CARS-1-62)the open project of key Laboratory of Jiangsu crop genomics and molecular Breeding(No.PL201902).
文摘The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived from the hybrid progenies of Wujing 13 and Milky Princess(Kantou 194)with polymorphism in soluble starch synthase gene SSIIa(SSII-3)and SSIIIa(SSIII-2)but no polymorphism in other starch synthase related genes were used as test materials.The genotypes of SSIIa and SSIIIa allele were identified by molecular markers,and the allelic effects of SSIIa and SSIIIa gene on amylose content(AC),gel consistency(GC),gelatinization temperature(GT)and rapid visco analyzer(RVA)profile characteristics were analyzed.The significant effects of SSIIa and SSIIIa alleles and the interactive effects between two genes on AC,GT,GC and RVA profile characteristics were found.The SSIIa and SSIIIa alleles from Wujing13 shown positive effects on AC with an average increase of 1.87 and 1.23%in 2 years respectively.There was no significant effect on GT for SSIIa or SSIIIa allele but remarkable influence on GT when the co-existence of the two genes.The genotype SSIIa^(mp)SSIIIa^(mp) shown 1.34℃higher GT than genotype SSIIawjSSIIIawj(mp and wj indicated that the gene was derived from Milky Princess and Wujing 13 respectively,the same as in the below).Different genes and alleles resulted in significant different GC.The genetic effect of SSIIawj and SSIIIamp on GC was 8.74 and 9.62mm respectively.The GC of SSIIa^(wj)SSIIIa^(mp) was 10.64 and 16.95mm higher than that of SSIIa^(mp)SSIIIa^(wj) and SSIIawjSSIIIawj,respectively.The allele SSIIa^(wj) could increase the peak viscosity(PKV),hot paste viscosity(HPV),cool paste viscosity(CPV)and breakdown viscosity(BDV),while decrease the consistency viscosity(CSV)and setback viscosity(SBV).However for the allele SSIIIa^(wj) the opposite was true.The genotype SSIIa^(wj)SSIIIa^(mp) had the largest PKV,HPV and CPV,the genotype SSIIa^(wj)SSIIIa^(wj) had the largest BDV and CSV,but the genotype SSIIa^(wj)SSIIIa^(mp) had the least SBV.According to the comprehensive effect of each trait,the genotype SSIIawjSSIIIamp was the best.The allelic variation and interaction effect of SSIIa and SSIIIa genes have important reference value for improving cooking and eating quality of semi waxy japonica rice.