Bacillus sp. CDB3 isolated from an arsenic contaminated cattledip site possesses an uncommon arsenic resistance （ars） operon bearing eight genes in the order of arsRYCDATorf7orf8. We investigated the functions of ar...Bacillus sp. CDB3 isolated from an arsenic contaminated cattledip site possesses an uncommon arsenic resistance （ars） operon bearing eight genes in the order of arsRYCDATorf7orf8. We investigated the functions of arsA, arsT, orf7 and orf8 in arsenic resistance using a plasmid-based gene knockout approach in the ars genedeficient Escherichia coli strain AW3110. The CDB3 arsA genewas shown to play a significant role in resistance, suggesting that the encoded ArsA may couplewith the arsenite transporter, forming an ArsAY complex that can enhance arsenite extrusion efficiency. Thedisruption of either arsT or orf7was not observed to affect arsenic resistance in the heterologous E. coli host, but their involvement in arsenic resistance can not be excluded. The orf8 gene is predicted to encode a putativedual-specificity protein phosphatasewhich also shares certain homology to arsenate reductases. The function loss of orf8 resulted in a remarkabledecrease in resistance to arsenate, though not arsenite. To examine if this effectwasdue to the reduction of arsenate by orf8, the arsC genewithin the 8-gene operonwasdisrupted. The resulting abolishment of arsenate resistance suggests that the involvement of orf8 in arsenic resistance is not via reductase activity.展开更多
Biogeochemical cyclic activity of the ars (arsenic resistance system) operon is arsB influx/effux encoded by the ecological of Pseudomonas putida.This suggests that studying arsenite-oxidizing bacteria may lead to a b...Biogeochemical cyclic activity of the ars (arsenic resistance system) operon is arsB influx/effux encoded by the ecological of Pseudomonas putida.This suggests that studying arsenite-oxidizing bacteria may lead to a better understanding of molecular geomicrobiology,which can be applied to the bioremediation of arsenic-contaminated mines.This is the first report in which multiple arsB-binding mechanisms have been used on indigenous bacteria.In ArsB (strains OS-5; ABB83931; OS-19; ABB04282 and RW-28; ABB88574...展开更多
The concentration and variational trend of As3 +and As 5+,the bacterial resistance for the As 3+and As 5+and converting conditions from As3 +to As 5+were analyzed.The additive was used to prompt the bacterial leaching...The concentration and variational trend of As3 +and As 5+,the bacterial resistance for the As 3+and As 5+and converting conditions from As3 +to As 5+were analyzed.The additive was used to prompt the bacterial leaching efficiency by changing valence state of arsenic.The results show that the concentration of As 3+ is larger than that of As 5+ in the lag phase.The concentration of As 3+ decreases in the log phase,and is lower than that of As5 +.HQ-0211 typed bacteria express better resistance for As 3+and As 5+and remain growing when the concentrations of As3 +and As 5+are above 6.0 g/L and 12.0 g/L,respectively.It is found that Fe 3+cannot oxidize As3 +singly as strong oxidant in the leaching system,but can cooperate with pyrite or chalcopyrite to do that.The oxidation of As 3+ is prompted with addition of H2O2.The bacterial activity is improved in favor of bacterial leaching efficiency.NaClO restrains the bacterial growth to depress leaching efficiency because of the chloric compounds affecting bacterial activity.展开更多
文摘Bacillus sp. CDB3 isolated from an arsenic contaminated cattledip site possesses an uncommon arsenic resistance （ars） operon bearing eight genes in the order of arsRYCDATorf7orf8. We investigated the functions of arsA, arsT, orf7 and orf8 in arsenic resistance using a plasmid-based gene knockout approach in the ars genedeficient Escherichia coli strain AW3110. The CDB3 arsA genewas shown to play a significant role in resistance, suggesting that the encoded ArsA may couplewith the arsenite transporter, forming an ArsAY complex that can enhance arsenite extrusion efficiency. Thedisruption of either arsT or orf7was not observed to affect arsenic resistance in the heterologous E. coli host, but their involvement in arsenic resistance can not be excluded. The orf8 gene is predicted to encode a putativedual-specificity protein phosphatasewhich also shares certain homology to arsenate reductases. The function loss of orf8 resulted in a remarkabledecrease in resistance to arsenate, though not arsenite. To examine if this effectwasdue to the reduction of arsenate by orf8, the arsC genewithin the 8-gene operonwasdisrupted. The resulting abolishment of arsenate resistance suggests that the involvement of orf8 in arsenic resistance is not via reductase activity.
基金the Korea Science and Engineering Foundation (KOSEF) through the National Research Lab.Program funded by the Korean Ministry of Science and Technology (No.M10300000298-06J0000-29810).
文摘Biogeochemical cyclic activity of the ars (arsenic resistance system) operon is arsB influx/effux encoded by the ecological of Pseudomonas putida.This suggests that studying arsenite-oxidizing bacteria may lead to a better understanding of molecular geomicrobiology,which can be applied to the bioremediation of arsenic-contaminated mines.This is the first report in which multiple arsB-binding mechanisms have been used on indigenous bacteria.In ArsB (strains OS-5; ABB83931; OS-19; ABB04282 and RW-28; ABB88574...
基金Projects(50674029, 50874030) supported by the National Natural Science Foundation of ChinaProject(2006AA06Z127) supported by the National High-tech Research and Development Program of ChinaProject(20060145015) supported by Specialized Research Fund for the Doctoral Program of Higher Education, China
文摘The concentration and variational trend of As3 +and As 5+,the bacterial resistance for the As 3+and As 5+and converting conditions from As3 +to As 5+were analyzed.The additive was used to prompt the bacterial leaching efficiency by changing valence state of arsenic.The results show that the concentration of As 3+ is larger than that of As 5+ in the lag phase.The concentration of As 3+ decreases in the log phase,and is lower than that of As5 +.HQ-0211 typed bacteria express better resistance for As 3+and As 5+and remain growing when the concentrations of As3 +and As 5+are above 6.0 g/L and 12.0 g/L,respectively.It is found that Fe 3+cannot oxidize As3 +singly as strong oxidant in the leaching system,but can cooperate with pyrite or chalcopyrite to do that.The oxidation of As 3+ is prompted with addition of H2O2.The bacterial activity is improved in favor of bacterial leaching efficiency.NaClO restrains the bacterial growth to depress leaching efficiency because of the chloric compounds affecting bacterial activity.
