Bacterial populations associated with the oxidation and reduction of arsenic in an unsaturated soil
Bacterial populations associated with the oxidation and reduction of arsenic in an unsaturated soil
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DOI：
10.1021/es034455a
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发表时间：
2004-01-01
影响因子：
11.4
通讯作者：
Inskeep, WP
中科院分区：
文献类型：
--
作者：
Macur, RE;Jackson, CR;Inskeep, WP
在用75 muM亚砷酸盐[As(III)]或250 muM砷酸盐[As(V)]处理的不饱和（好氧）土壤柱中，研究了负责As氧化和还原的微生物种群。亚砷酸盐[As(III)]通过微生物活性迅速氧化为As(V)，而在柱实验中没有观察到As(V)的明显还原。从同一色谱柱中分离出8株不同As氧化还原表型的好氧异养菌。3株分离物（基于16S序列）均为as （III）氧化剂，分别为农杆菌、荧光假单胞菌和似异变单胞菌（Variovorax paradoxus-like organisms），均在PCR结合变性梯度凝胶电泳生成的群落DNA指纹图谱中检测到。另外5个分离株（16S基因序列）分别为A. tummefaciens、Flavobacterium sp.、Microbacterium sp.和2个Arthrobacter sp.样生物，在有氧条件下可快速还原as (V)。虽然这两株肿瘤分枝杆菌样分离株表现出相反的As氧化还原活性，但它们的16S rDNA序列（相似于1400 bp）是100%相同的，并且都被证明含有假定的arsC基因。我们的研究结果支持了能够氧化As（III）或还原As(V)的细菌在土壤环境中共存和普遍存在的假设，表明特定微生物种群的相对丰度和代谢活性在土壤孔隙水中无机As的形态形成中起着重要作用。
Microbial populations responsible for the oxidation and reduction of As were examined in unsaturated (aerobic) soil columns treated with 75 muM arsenite [As(III)] or 250 muM arsenate [As(V)]. Arsenite [As(III)] was rapidly oxidized to As(V) via microbial activity, whereas no apparent reduction of As(V) was observed in the column experiments. Eight aerobic heterotrophic bacteria with varying As redox phenotypes were isolated from the same columns. Three isolates, identified as Agrobacterium tumefaciens-, Pseudomonas fluorescens, and Variovorax paradoxus-like organisms (based on 16S sequence), were As(III) oxidizers, and all were detected in community DNA fingerprints generated by PCR coupled with denaturing gradient gel electrophoresis. The five other isolates were identified (16S gene sequence) as A. tumefaciens, Flavobacterium sp., Microbacterium sp., and two Arthrobacter sp.-like organisms and were shown to rapidly reduce As(V) under aerobic conditions. Although the two A. tumefaciens-like isolates exhibited opposite As redox activity,their 16S rDNA sequences (similar to1400 bp) were 100% identical, and both were shown to contain putative arsC genes. Our results support the hypothesis that bacteria capable of either oxidizing As(III) or reducing As(V) coexist and are ubiquitous in soil environments, suggesting that the relative abundance and metabolic activity of specific microbial populations plays an important role in the speciation of inorganic As in soil pore waters.