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| 購買進口儀器、試劑和耗材——就在始于2001年的畢特博生物 www.mobfastly.com |
美國波多黎各泛美大學的研究者在新一期英國《BMC生物科技》雜志上報告說，他們用轉基因手段對一些細菌進行改造，使其含有能生成金屬硫化物和多磷酸鹽激酶的基因。實驗顯示，這種細菌能抵抗高濃度汞，即使汞濃度達到致死普通細菌的24倍，它仍能存活。 此外，這種細菌還能吸收環境中的汞，將其轉移到自己內部。實驗顯示，在高濃度汞溶液中，它可以在5天內從溶液中清除80%的汞。 領導研究的奧斯卡·魯伊斯說，這些轉基因細菌不僅可用于清除環境中的汞污染，而且在細菌內部逐漸聚集大量汞之后，還可以設法回收這些汞，供工業生產循環使用。 汞又稱水銀，是常溫下唯一的液態金屬，許多溫度計中都含有汞。汞如果散布到環境中，可以形成甲基汞等毒性物質，通過呼吸道等途徑侵入人體，或是被動植物吸收再通過食物鏈傳遞給人，造成汞中毒。 Characterization of mercury bioremediation by transgenic bacteria expressing metallothionein and polyphosphate kinase Oscar Ruiz, Derry Alvarez, Gloriene Gonzalez-Ruiz, Cesar Torres (provisional)Background The use of transgenic bacteria has been proposed as a suitable alternative for mercury remediation. Ideally, mercury would be sequestered by metal-scavenging agents inside transgenic bacteria for subsequent retrieval. So far, this approach has produced limited protection and accumulation. We report here the development of a transgenic system that effectively expresses metallothionein (mt-1) and polyphosphate kinase (ppk) genes in bacteria in order to provide high mercury resistance and accumulation. Results In this study, bacterial transformation with transcriptional and translational enhanced vectors designed for the expression of metallothionein and polyphosphate kinase provided high transgene transcript levels independent of the gene being expressed. Expression of polyphosphate kinase and metallothionein in transgenic bacteria provided high resistance to mercury, up to 80 microM and 120 microM, respectively. Here we show for the first time that metallothionein can be efficiently expressed in bacteria without being fused to a carrier protein to enhance mercury bioremediation. Cold vapor atomic absorption spectrometry analyzes revealed that the mt-1 transgenic bacteria accumulated up to 100.2 +/-17.6 microM of mercury from media containing 120 microM Hg. The extent of mercury remediation was such that the contaminated media remediated by the mt-1 transgenic bacteria supported the growth of untransformed bacteria. Cell aggregation, precipitation and color changes were visually observed in mt-1 and ppk transgenic bacteria when these cells were grown in high mercury concentrations. Conclusion The transgenic bacterial system described in this study presents a viable technology for mercury bioremediation from liquid matrices because it provides high mercury resistance and accumulation while inhibiting elemental mercury volatilization. This is the first report that shows that metallothionein expression provides mercury resistance and accumulation in recombinant bacteria. The high accumulation of mercury in the transgenic cells could present the possibility of retrieving the accumulated mercury for further industrial applications.
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購買進口儀器、試劑和耗材——就在始于2001年的畢特博生物
www.mobfastly.com |
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受到汞污染的環境對人和許多生物都有害，但一項新研究顯示，用轉基因技術培育的一種細菌，不僅可在含高濃度汞的環境中存活，還能清除汞，減少污染。