University of Bordeaux, CNRS, Fundamental Microbiology and Pathogenicity Laboratory, European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607, Pessac, France.
University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Croatia.
Chemosphere. 2020 Jun;248:126002. doi: 10.1016/j.chemosphere.2020.126002. Epub 2020 Jan 22.
A mercury-resistant bacterial strain has been isolated from a rock of the Idrija mercury mine in Slovenia. The rock had 19 g carbon and 2952 mg mercury (Hg) per kg. Mass spectrometry and DNA sequencing showed that the bacterium belongs to the Pseudomonas genus. It is called Pseudomonas idrijaensis. This bacterial strain is sensitive to methylmercury (MeHg) like the reference P. aeruginosa strain PAO1, and is resistant to divalent mercury (Hg(II)) in contrast to PAO1. This difference could be attributed to the presence of the mer operon yet deprived of the merB gene encoding the organomercurial lyase, on the basis of whole genome sequencing. The P. idrijaensis mer operon displays the RTPCADE organization and is contained in the Tn5041 transposon. This transposon identified here occurs in other Gram-negative Hg-resistant strains isolated from mercury ores, aquatic systems and soils, including Pseudomonas strains from 15,000 to 40,000 years old Siberian permafrost. When P. idrijaensis was exposed to mercury chloride, two intracellular Hg species were identified by high energy-resolution XANES spectroscopy, a dithiolate Hg(SR) and a tetrathiolate Hg(SR) complex. P. idrijaensis had a much higher [Hg(SR)]/[Hg(SR)] molar ratio than bacteria lacking the mer operon when exposed to 4 μg Hg/L - resulting in an intracellular accumulation of 4.3 μg Hg/g dw. A higher amount of the Hg(SR) complex provides a chemical signature for the expression of the dicysteinate Mer proteins in response to mercury toxicity.
从斯洛文尼亚伊德里亚汞矿的一块岩石中分离出一株耐汞细菌。这块岩石含有 19 克碳和 2952 毫克汞（Hg）/公斤。质谱和 DNA 测序表明，该细菌属于假单胞菌属。它被称为伊德里亚假单胞菌。与参考菌株 P. aeruginosa PAO1 一样，该细菌菌株对甲基汞（MeHg）敏感，并且与 PAO1 不同，对二价汞（Hg(II)）具有抗性。根据全基因组测序，这种差异可能归因于 mer 操纵子的存在，而缺乏编码有机汞裂解酶的 merB 基因。P. idrijaensis mer 操纵子显示 RTPCADE 组织，并且包含在 Tn5041 转座子中。这里鉴定的这种转座子存在于其他从汞矿石、水生系统和土壤中分离出的革兰氏阴性耐汞菌株中，包括来自 15000 到 40000 年前西伯利亚永冻土的假单胞菌菌株。当 P. idrijaensis 暴露于氯化汞时，通过高能分辨 XANES 光谱鉴定出两种细胞内 Hg 物种，一种是二硫代 Hg(SR)和一种四硫代 Hg(SR)络合物。与缺乏 mer 操纵子的细菌相比，当暴露于 4μg/L Hg 时，P. idrijaensis 的[Hg(SR)]/[Hg(SR)]摩尔比高得多 - 导致细胞内积累 4.3μg Hg/g dw。更多的 Hg(SR)络合物提供了表达二半胱氨酸 Mer 蛋白以应对汞毒性的化学特征。
