Research Center for Analytical Sciences, Box 332, Northeastern University , Shenyang 110819, China.
Environ Sci Technol. 2012 Feb 21;46(4):2251-6. doi: 10.1021/es204034z. Epub 2012 Feb 3.
Bacillus subtilis is a spore forming bacterium that takes up both inorganic As(III) and As(V). Incubating the bacteria with Fe(III) causes iron uptake (up to ∼0.5% w/w), and some of the iron attaches to the cell membrane as hydrous ferric oxide (HFO) with additional HFO as a separate phase. Remarkably, 30% of the Bacillus subtilis cells remain viable after treatment by 8 mM Fe(III). At pH 3, upon metalation, As(III) binding capacity becomes ∼0, while that for As(V) increases more than three times, offering an unusual high selectivity for As(V) against As(III). At pH 10 both arsenic forms are sorbed, the As(V) sorption capacity of the ferrated Bacillus subtilis is at least of 11 times higher than that of the native bacteria. At pH 8 (close to pH of most natural water), the arsenic binding capacity per mole iron for the ferrated bacteria is greater than those reported for any iron containing sorbent. A sensitive arsenic speciation approach is thus developed based on the binding of inorganic arsenic species by the ferrated bacteria and its unusual high selectivity toward As(V) at low pH.
枯草芽孢杆菌是一种形成孢子的细菌，能够同时吸收无机砷（III）和砷（V）。将细菌与三价铁（Fe(III)）一起孵育会导致铁的吸收（高达约 0.5%w/w），并且一些铁会附着在细胞膜上，形成水合氧化铁（HFO），还有一部分 HFO 则是作为单独的相存在。值得注意的是，枯草芽孢杆菌在经过 8mM 三价铁处理后，有 30%的细胞仍然具有活力。在 pH 3 下，金属化后，砷（III）的结合能力变为约 0，而砷（V）的结合能力增加了三倍以上，对砷（V）表现出异常高的选择性，而对砷（III）则没有。在 pH 10 下，两种砷形态都被吸附，ferrated 枯草芽孢杆菌对砷（V）的吸附能力至少比天然细菌高 11 倍。在接近大多数天然水的 pH 值 8 下，ferrated 细菌的每摩尔铁的砷结合能力大于任何含铁吸附剂的报道值。因此，基于 ferrated 细菌对无机砷物种的结合及其在低 pH 值下对砷（V）的异常高选择性，开发了一种灵敏的砷形态分析方法。
