Life at the energetic edge: Kinetics of circumneutral iron oxidation by lithotrophic iron-oxidizing bacteria isolated from the wetland-plant rhizosphere
Life at the energetic edge: Kinetics of circumneutral iron oxidation by lithotrophic iron-oxidizing bacteria isolated from the wetland-plant rhizosphere
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DOI：
10.1128/aem.68.8.3988-3995.2002
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发表时间：
2002-08-01
影响因子：
4.4
通讯作者：
Megonigal, JP
中科院分区：
文献类型：
--
作者：
Neubauer, SC;Emerson, D;Megonigal, JP
批培养的石营养型Fe（II）氧化细菌，菌株BrT，从湿地植物的根际分离，生长在生物反应器中，并用于确定微生物的Fe（II）氧化的意义在circumneutral pH值，并确定非生物变量，影响微生物氧化和化学氧化之间的分区。菌株BrT只在Fe（II）源的存在下生长，平均倍增时间为25 h。在一组实验中，在用叠氮化钠使细胞中毒之前和之后测量Fe（II）氧化速率。这些实验表明，菌株BrT占18至53%的总铁氧化，和平均细胞生长产量为0.70克的CH 2 O每摩尔的Fe（II）氧化。在第二组实验中，Fe（II）不断加入到接种活细胞、死细胞或无细胞的生物反应器中。实验数据拟合的统计模型表明，代谢Fe（II）氧化占总氧化的62%。在这些实验中的总Fe（II）的氧化速率受到强烈限制的Fe（II）交付到系统的速率，也受到O-2和总铁浓度的影响。此外，该模型表明，微生物抑制非生物Fe（II）氧化的速率，可能是通过将Fe（II）与细菌外聚合物结合。菌株BrT的净效应是加速总氧化速率高达18%，与无细胞处理获得的速率相比。结果表明，嗜盐Fe（II）氧化细菌可能竞争有限的O-2在根际，从而影响其他湿地生态地球化学循环。
Batch cultures of a lithotrophic Fe(II)-oxidizing bacterium, strain BrT, isolated from the rhizosphere of a wetland plant, were grown in bioreactors and used to determine the significance of microbial Fe(II) oxidation at circumneutral pH and to identify abiotic variables that affect the partitioning between microbial oxidation and chemical oxidation. Strain BrT grew only in the presence of an Fe(II) source, with an average doubling time of 25 h. In one set of experiments, Fe(II) oxidation rates were measured before and after the cells were poisoned with sodium azide. These experiments indicated that strain BrT accounted for 18 to 53% of the total iron oxidation, and the average cellular growth yield was 0.70 g of CH2O per mol of Fe(II) oxidized. In a second set of experiments, Fe(II) was constantly added to bioreactors inoculated with live cells, killed cells, or no cells. A statistical model fitted to the experimental data demonstrated that metabolic Fe(II) oxidation accounted for up to 62% of the total oxidation. The total Fe(II) oxidation rates in these experiments were strongly limited by the rate of Fe(II) delivery to the system and were also influenced by O-2 and total iron concentrations. Additionally, the model suggested that the microbes inhibited rates of abiotic Fe(II) oxidation, perhaps by binding Fe(II) to bacterial exopolymers. The net effect of strain BrT was to accelerate total oxidation rates by up to 18% compared to rates obtained with cell-free treatments. The results suggest that neutrophilic Fe(II)oxidizing bacteria may compete for limited O-2 in the rhizosphere and therefore influence other wetland biogeochemical cycles.