Rhine E Danielle, Garcia-Dominguez Elizabeth, Phelps Craig D, Young L Y
Biotechnology Center for Agriculture and the Environment, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA.
Environ Sci Technol. 2005 Dec 15;39(24):9569-73. doi: 10.1021/es051047t.
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(II) 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 As(V). 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.
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，并且能够被微生物轻易地氧化或还原。鉴于地下水中砷带来的健康风险以及对砷活性微生物的关注，我们推测环境微生物能够介导与它们的新陈代谢相关的砷的氧化还原循环。使用从纽约州锡拉丘兹市一个超级基金场地奥农达加湖分离出的一株As(V)呼吸还原菌（菌株Y5）和一株需氧化学自养型As(II)氧化菌（菌株OL1）对这一假设进行了验证。菌株分别在密封血清瓶中单独培养和共同培养，唯一改变的参数是有氧/无氧条件。最初，在无氧条件下将两种菌株共同培养时，2 mM的As(V)在14天内按化学计量比还原为As(III)。完全还原后，加入无菌环境空气，24小时内As(III)完全氧化为As(V)。重复无氧-有氧循环，无菌对照显示在28天的培养期内没有非生物转化。这些结果表明，微生物能够响应动态环境条件使砷循环，从而影响砷在环境中的形态，进而影响其迁移性和毒性。
