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首页> 外文期刊>Journal of bacteriology >Identification of intrinsic high-level resistance to rare-earth oxides and oxyanions in members of the class Proteobacteria: characterization of tellurite, selenite, and rhodium sesquioxide reduction in Rhodobacter sphaeroides.
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Identification of intrinsic high-level resistance to rare-earth oxides and oxyanions in members of the class Proteobacteria: characterization of tellurite, selenite, and rhodium sesquioxide reduction in Rhodobacter sphaeroides.

机译：鉴定对Proteobacteria类成员中的稀土氧化物和氧阴离子具有内在的高水平抗性：球形红细菌中亚碲酸盐，亚硒酸盐和三氧化二铑还原的表征。

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We have identified intrinsic high-level resistance (HLR) to tellurite, selenite, and at least 15 other rare-earth oxides and oxyanions in the facultative photoheterotroph Rhodobacter sphaeroides grown either chemoheterotrophically or photoheterotrophically. Other members of the class Proteobacteria, including members of the alpha-2 and alpha-3 phylogenetic subgroups, were also shown to effect the reduction of many of these compounds, although genera from the alpha-1, beta-1, and gamma-3 subgroups did not express HLR to the oxyanions examined. Detailed analyses employing R. sphaeroides have shown that HLR to at least one class of these oxyanions, the tellurite class (e.g., tellurate, tellurite, selenate, selenite, and rhodium sesquioxide), occurred via intracellular oxyanion reduction and resulted in deposition of metal in the cytoplasmic membrane. The concomitant evolution of hydrogen gas from cells grown photoheterotrophically in the presence of these oxyanions was also observed. HLR to tellurite class oxyanions in R. sphaeroides was not affected by exogenous methionine or phosphate but was reduced 40-fold by the addition of cysteine to growth media. In contrast HLR to the periodate class oxyanions (e.g., periodate, siliconate, and siliconite) was inhibited by extracellular PO4(3-) but did not result in metal deposition or gas evolution. Finally, we observed that HLR to arsenate class oxyanions (e.g., arsenate, molybdate, and tungstate) occurred by a third, distinct mechanism, as evidenced by the lack of intracellular metal deposition and hydrogen gas evolution and an insensitivity to extracellular PO4(3-) or cysteine. Examination of a number of R. sphaeroides mutants has determined the obligate requirement for an intact CO2 fixation pathway and the presence of a functional photosynthetic electron transport chain to effect HLR to K2TeO3 under photosynthetic growth conditions, whereas functional cytochromes bc1 and c2 were required under aerobic growth conditions to facilitate HLR. Finally, a purification scheme to recover metals from intact bacterial cells was developed.
机译：我们已经确定了对兼化学光养或光养营养的球形杂合红球菌红球菌，亚硒酸盐以及至少15种其他稀土氧化物和氧阴离子的内在高水平抗性（HLR）。尽管属于α-1，β-1和γ-3属，但也显示了变形杆菌类的其他成员，包括α-2和α-3系统发育亚组的成员。亚组未对所检测的氧阴离子表达HLR。详细的分析表明，对球形含氧阴离子的HLR通过细胞内含氧阴离子的还原而发生，并导致金属在金属中的沉积。HLR对这些含氧阴离子中的至少一类（亚碲酸盐类，亚碲酸盐，硒酸盐，亚硒酸盐和倍半氧化铑）发生了HLR。细胞质膜还观察到在这些氧阴离子的存在下，氢从光异养生长的细胞中伴随释放出来。球形红球藻中亚碲酸盐类含氧阴离子的HLR不受外源蛋氨酸或磷酸盐的影响，但通过向生长培养基中添加半胱氨酸使其减少40倍。相反，HLR与高碘酸盐类含氧阴离子（例如，高碘酸盐，硅酸盐和亚硅酸盐）被细胞外PO4（3-）抑制，但不会导致金属沉积或气体逸出。最后，我们观察到HLR可以通过第三种独特的机理发生砷酸类氧阴离子（例如，砷酸根，钼酸根和钨酸根），这是由于缺乏细胞内金属沉积和氢气释放以及对细胞外PO4不敏感所致（3- ）或半胱氨酸。对许多球形拟南芥突变体的检查已确定了完整的CO2固定途径的必要条件，以及在光合作用的生长条件下存在功能性光合电子传输链以影响HLR对K2TeO3的作用，而有氧条件下需要功能性细胞色素bc1和c2生长条件促进HLR。最后，开发了从完整细菌细胞中回收金属的纯化方案。

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