Microbiology Department, Biologic Science Faculty, University of Concepción, P.O. Box 160-C, Correo 3, Concepción, Chile.
Arch Environ Contam Toxicol. 2011 Aug;61(2):185-92. doi: 10.1007/s00244-010-9601-7. Epub 2010 Sep 22.
The arsenic biogeochemical cycle is greatly dependent on microbial transformations that affect both the distribution and mobility of arsenic species in the environment. In this study, a microbial biofilm from volcanic rocks was characterized on the basis of its bacterial composition and ability to mobilize arsenic under circumneutral pH. Biofilm microstructure was analyzed by scanning electron microscopy (SEM)-energy-dispersive spectroscopy (EDS). Strains were isolated from biofilms and identified by 16S rDNA sequences analysis. Arsenic oxidation and reduction capacity was assayed with high-performance liquid chromatography coupled to gaseous formation performing the detection by atomic absortion in a quartz bucket (HPLC/HG/QAAS), and polymerase chain reaction was used to detect aox and ars genes. Bacterial communities associated with volcanic rocks were studied by denaturing gradient gel electrophoresis (DGGE). The SEM-EDS studies showed the presence of biofilm after 45 days of incubation. The relative closest GenBank matches of the DNA sequences, of isolated arsenic-resistant strains, showed the existence of four different genus: Burkholderia, Pseudomonas, Erwinia, and Pantoea. Four arsenite-resistant strains were isolates, and only three strains were able to oxidize >97% of the As(III) present (500 uM). All arsenate-resistant isolates were able to reduce between 69 and 86% of total As(V) (1000 uM). Analysis of 16S rDNA sequences obtained by DGGE showed the presence of four bacterial groups (∝-proteobacteria, γ-proteobacteria, Firmicutes, and Actinobacteria). Experiments demonstrate that epilithic bacterial communities play a key role in the mobilization of arsenic and metalloids speciation.
砷的生物地球化学循环在很大程度上依赖于微生物转化，这些转化影响了砷在环境中的分布和迁移。在这项研究中，基于其在中性 pH 条件下对砷的微生物生物膜的细菌组成和迁移能力进行了特征描述。使用扫描电子显微镜（SEM）-能量色散光谱（EDS）分析生物膜的微观结构。从生物膜中分离出菌株，并通过 16S rDNA 序列分析进行鉴定。采用高效液相色谱与气相形成法（HPLC/HG/QAAS）进行砷氧化和还原能力的测定，聚合酶链反应（PCR）用于检测 aox 和 ars 基因。通过变性梯度凝胶电泳（DGGE）研究与火山岩相关的细菌群落。SEM-EDS 研究表明，在孵育 45 天后存在生物膜。与耐砷分离菌株的 DNA 序列的相对最接近的 GenBank 匹配显示存在四个不同的属：伯克霍尔德氏菌、假单胞菌、欧文氏菌和泛菌。分离出了四种亚砷酸盐抗性菌株，只有三种菌株能够氧化 >97%的存在的 As(III)（500μM）。所有砷酸盐抗性分离株均能够还原 69-86%的总 As(V)（1000μM）。DGGE 获得的 16S rDNA 序列分析表明存在四个细菌群（α-变形菌、γ-变形菌、Firmicutes 和 Actinobacteria）。实验表明，附生细菌群落在砷和类金属的形态迁移中起着关键作用。
