Environmental microbes can speciate and cycle arsenic
Environmental microbes can speciate and cycle arsenic
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DOI：
10.1021/es051047t
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发表时间：
2005-12-15
影响因子：
11.4
通讯作者：
Young, LY
中科院分区：
文献类型：
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作者：
Rhine, ED;Garcia-Dominguez, E;Young, LY
天然存在的砷主要以砷酸盐[As（V）]或亚砷酸盐[As（III）]的形式存在，并且很容易被微生物氧化或还原。考虑到与地下水中砷相关的健康风险和对砷活性微生物的兴趣，我们假设环境微生物可以介导与其代谢相关的砷的氧化还原循环。使用As（V）呼吸还原剂（菌株Y 5）和有氧化能自养As（III）氧化剂（菌株OL 1）对这一假设进行了测试，这两种还原剂和氧化剂均分离自纽约州锡拉丘兹奥农达加湖的超级基金站点。菌株在密封的血清瓶中分别和一起生长，并且好氧/缺氧条件是唯一改变的参数。最初，在缺氧条件下，当两个分离株生长在一起，2 mM As（V）的化学计量减少到As（III）在14天内。完全还原后，加入无菌环境空气，在24小时内As（III）完全氧化为AsM。重复缺氧-好氧循环，无菌对照在28天孵育期内未显示非生物转化。这些结果表明，微生物可以响应动态的环境条件下循环砷，从而影响形态，因此流动性和毒性的砷在环境中。
Naturally occurring arsenic is found predominantly as arsenate [As(V)] or arsenite [As(III)], and can be readily oxidized or reduced by microorganisms. Given the health risks associated with arsenic in groundwater and the interest in arsenic-active microorganisms, we hypothesized that environmental microorganisms could mediate a redox cycling of arsenic that is linked to their metabolism. This hypothesis was tested using an As(V) respiring reducer (strain Y5) and an aerobic chemoautotrophic As(III) oxidizer (strain OL1) both isolated from a Superfund site, Onondaga Lake, in Syracuse, NY. Strains were grown separately and together in sealed serum bottles, and the oxic/anoxic condition was the only parameter changed. Initially, under anoxic conditions when both isolates were grown together, 2 mM As(V) was stoichiometrically reduced to As(III) within 14 days. Following complete reduction, sterile ambient air was added and within 24 h As(III) was completely oxidized to AsM. The anoxic-oxic cycle was repeated, and sterile controls showed no abiotic transformation within the 28-day incubation period. These results demonstrate that microorganisms can cycle arsenic in response to dynamic environmental conditions, thereby affecting the speciation, and hence mobility and toxicity of arsenic in the environment.