當(dāng)與真菌(Metarhizium anisopliae)一起培育時(shí),，鉛彈頭上形成磷氯鉛礦和其他鉛金屬礦。圖片來自Geoffrey Michael Gadd,。
根據(jù)2012年1月12日在線發(fā)表在Cell子刊Current Biology上的一篇研究論文,，某種真菌物種能夠?qū)U金屬轉(zhuǎn)化為磷氯鉛礦(pyromorphite)。這些發(fā)現(xiàn)著重表明微生物在地質(zhì)作用中發(fā)揮著重要作用,，提示著一種可能的生物修復(fù)鉛污染土壤的方法。這也是真菌起著將鉛金屬礦物質(zhì)化作用的第一個(gè)例子,。
眾所周知鉛金屬是劇毒的,。因?yàn)殂U牽涉到兒童早期的神經(jīng)發(fā)育問題，在諸如家用油漆之類的產(chǎn)品中該金屬已經(jīng)被剔除出去,，但是仍然存在其他的鉛污染源,，比如采礦作業(yè)和射擊場(chǎng)中所用的能夠浸染土壤的子彈。一旦進(jìn)入土壤里面,，鉛金屬能夠滲入到水源,，進(jìn)入食物鏈。
鉛金屬暴露在大氣,、濕度和pH中能夠產(chǎn)生鉛氧化物和鉛鹽,。修復(fù)鉛污染土壤的策略的著重點(diǎn)是將鉛轉(zhuǎn)化為最穩(wěn)定形式的磷氯鉛礦。已知真菌能夠讓諸如鈾之類的其他毒性化合物去毒,，去毒方式就是將它們轉(zhuǎn)換為礦物形式,。因此來自英國鄧迪大學(xué)的Geoff Gadd推斷真菌也可能對(duì)鉛做同樣的事情。
Gadd領(lǐng)導(dǎo)的研究小組在蘇格蘭一個(gè)廢棄的鉛采礦作業(yè)場(chǎng)所采集了幾種真菌物種樣品,。他們將鉛彈頭(用于散彈槍中的彈藥)放置在培養(yǎng)皿里的瓊脂糖培養(yǎng)基中,，然后再加入真菌到一些培養(yǎng)皿中，讓它們生長(zhǎng)幾個(gè)月,。
通過分析堆積在鉛上面的化合物的元素組成和礦物結(jié)構(gòu),，研究人員發(fā)現(xiàn)，相比于將鉛金屬放置在滅過菌的培養(yǎng)皿中,，與某種真菌物種孵育的鉛金屬產(chǎn)生更高水平的磷氯鉛礦,，這就意味著這種真菌確實(shí)發(fā)揮著將鉛金屬去毒化的作用。
鑒于當(dāng)前人們還不能將污染土壤中的所有鉛金屬全部去除,，Gadd認(rèn)為這種真菌溶解金屬元素的能力可能被用作一種修復(fù)策略,。
將鉛金屬礦物質(zhì)化的真菌可能是一種未來的生物修復(fù)策略，但是首要工作就是能夠在實(shí)驗(yàn)室外重復(fù)這些研究結(jié)果,。生物修復(fù)是一種黑盒測(cè)試方法,，只有獲得關(guān)鍵性證據(jù)，如真菌如何參與當(dāng)中,，就能夠幫助科學(xué)家設(shè)計(jì)出長(zhǎng)期修復(fù)策略以便修復(fù)受污染的土地,。(生物谷：towersimper編譯)
doi:10.1016/j.cub.2011.12.017
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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.
