Curr. Biol.：首次发现将铅金属转化为磷氯铅矿的真菌

根据2012年1月12日在线发表在Cell子刊Current Biology上的一篇研究论文，某种真菌物种能够将铅金属转化为磷氯铅矿(pyromorphite)。这些发现着重表明微生物在地质作用中发挥着重要作用，提示着一种可能的生物修复铅污染土壤的方法。这也是真菌起着将铅金属矿物质化作用的第一个例子。

众所周知铅金属是剧毒的。因为铅牵涉到儿童早期的神经发育问题，在诸如家用油漆之类的产品中该金属已经被剔除出去，但是仍然存在其他的铅污染源，比如采矿作业和射击场中所用的能够浸染土壤的子弹。一旦进入土壤里面，铅金属能够渗入到水源，进入食物链。

铅金属暴露在大气、湿度和pH中能够产生铅氧化物和铅盐。修复铅污染土壤的策略的着重点是将铅转化为最稳定形式的磷氯铅矿。已知真菌能够让诸如铀之类的其他毒性化合物去毒，去毒方式就是将它们转换为矿物形式。因此来自英国邓迪大学的Geoff Gadd推断真菌也可能对铅做同样的事情。

Gadd领导的研究小组在苏格兰一个废弃的铅采矿作业场所采集了几种真菌物种样品。他们将铅弹头(用于散弹枪中的弹药)放置在培养皿里的琼脂糖培养基中，然后再加入真菌到一些培养皿中，让它们生长几个月。

通过分析堆积在铅上面的化合物的元素组成和矿物结构，研究人员发现，相比于将铅金属放置在灭过菌的培养皿中，与某种真菌物种孵育的铅金属产生更高水平的磷氯铅矿，这就意味着这种真菌确实发挥着将铅金属去毒化的作用。

鉴于当前人们还不能将污染土壤中的所有铅金属全部去除，Gadd认为这种真菌溶解金属元素的能力可能被用作一种修复策略。

将铅金属矿物质化的真菌可能是一种未来的生物修复策略，但是首要工作就是能够在实验室外重复这些研究结果。生物修复是一种黑盒测试方法，只有获得关键性证据，如真菌如何参与当中，就能够帮助科学家设计出长期修复策略以便修复受污染的土地。

Lead Transformation to Pyromorphite by Fungi

Young Joon Rhee, Stephen Hillier, Geoffrey Michael Gadd

Lead (Pb) is a serious environmental pollutant in all its chemical forms. Attempts have been made to immobilize lead in soil as the mineral pyromorphite using phosphate amendments (e.g., rock phosphate, phosphoric acid, and apatite), although our work has demonstrated that soil fungi are able to transform pyromorphite into lead oxalate. Lead metal, an important structural and industrial material, is subject to weathering, and soil contamination also occurs through hunting and shooting. Although fungi are increasingly appreciated as geologic agents, there is a distinct lack of knowledge about their involvement in lead geochemistry. We examined the influence of fungal activity on lead metal and discovered that metallic lead can be transformed into chloropyromorphite, the most stable lead mineral that exists. This is of geochemical significance, not only regarding lead fate and cycling in the environment but also in relation to the phosphate cycle and linked with microbial transformations of inorganic and organic phosphorus. This paper provides the first report of mycogenic chloropyromorphite formation from metallic lead and highlights the significance of this phenomenon as a biotic component of lead biogeochemistry, with additional consequences for microbial survival in lead-contaminated environments and bioremedial treatments for Pb-contaminated land.

文献链接：http://www.cell.com/current-biology/abstract/S0960-9822(11)01392-3