Acidithiobacillus ferrooxidans is an acidophilic bacterium able to grow in environments with high concentrations of metals. It is a chemolithoautotroph able to form biofilms on the surface of solid minerals to obtain its energy. The response of both planktonic and sessile cells of A. ferrooxidans ATCC 23270 grown in elemental sulfur and adapted to high copper concentration was analyzed by quantitative proteomics. It was found that 137 proteins varied their abundance when comparing both lifestyles. Copper effllux proteins, some subunits of the ATP synthase complex, porins, and proteins involved in cell wall modification increased their abundance in copper-adapted sessile lifestyle cells. On the other hand, planktonic copper-adapted cells showed increased levels of proteins such as: cupreredoxins involved in copper cell sequestration, some proteins related to sulfur metabolism, those involved in biosynthesis and transport of lipopolysaccharides, and in assembly of type IV pili. During copper adaptation a decreased formation of biofilms was measured as determined by epifluorescence microscopy. This was apparently due not only to a diminished number of sessile cells but also to their exopolysaccharides production. This is the first study showing that copper, a prevalent metal in biomining environments causes dispersion of A. ferrooxidans biofilms.

Significance

Copper is a metal frequently found in high concentrations at mining environments inhabitated by acidophilic microorganisms. Copper resistance determinants of A. ferrooxidans have been previously studied in planktonic cells. Although biofilms are recurrent in these types of environments, the effect of copper on their formation has not been studied so far. The results obtained indicate that high concentrations of copper reduce the capacity of A. ferrooxidans ATCC 23270 to form biofilms on sulfur. These findings may be relevant to consider for a bacterium widely used in copper bioleaching processes.

中文翻译：

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高铜浓度可通过减少细胞外聚合物质的产生及其对元素硫的附着力来减少氧化亚铁硫杆菌中生物膜的形成。

酸性氧化铁硫杆菌是一种嗜酸细菌，能够在金属含量高的环境中生长。它是一种化石自养生物，能够在固体矿物质的表面形成生物膜以获得其能量。铁氧化拟南芥浮游和无柄细胞的反应通过定量蛋白质组学分析了在元素硫中生长并适应高铜浓度的ATCC 23270。比较两种生活方式时，发现137种蛋白质的丰度不同。铜外排蛋白，ATP合酶复合物的一些亚基，孔蛋白和参与细胞壁修饰的蛋白增加了它们在铜适应的无柄生活方式细胞中的丰度。另一方面，浮游生物适应铜的细胞显示出增加的蛋白质水平，例如：铜细胞隔离所涉及的铜氧化还原蛋白，一些与硫代谢有关的蛋白质，与脂多糖的生物合成和运输有关的蛋白质以及IV型菌毛的组装。在铜适应过程中，通过落射荧光显微镜确定了生物膜形成的减少。显然，这不仅是由于无柄细胞数量减少，而且还由于它们的胞外多糖产生。这是第一项研究表明，铜是生物采矿环境中的一种普遍金属，会导致A.氧化铁生物膜。

意义

铜是在嗜酸性微生物居住的采矿环境中经常发现的高浓度金属。先前已经在浮游细胞中研究过氧化铁农杆菌的铜抗性决定子。尽管在这些类型的环境中会经常出现生物膜，但到目前为止，尚未研究铜对其形成的影响。所获得的结果表明，高浓度的铜会降低A.ferrooxidans ATCC 23270在硫上形成生物膜的能力。这些发现可能与考虑广泛用于铜生物浸出过程的细菌有关。