Did mineral surface chemistry and toxicity contribute to evolution of microbial extracellular polymeric substances?
Did mineral surface chemistry and toxicity contribute to evolution of microbial extracellular polymeric substances?
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矿物表面化学和毒性是否有助于微生物细胞外聚合物的进化？
DOI：
10.1089/ast.2011.0776
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发表时间：
2012
期刊：
影响因子：
4.2
通讯作者：
Sahai,Nita
中科院分区：
文献类型：
--
作者：
Xu,Jie;Campbell,JayM;Zhang,Nianli;Hickey,WilliamJ;Sahai,Nita
现代生态位在与矿物表面密切相关的生物膜中充满了惊人的微生物多样性，这凸显了微生物在克服矿物-水界面的挑战和利用其带来的好处方面取得的巨大成功。 Biofilm formation capability likely evolved on early Earth because biofilms provide crucial cell survival functions.然而，矿物质表面对细胞的潜在毒性以及矿物质-水-细胞界面在确定毒性机制方面的复杂性尚未得到充分认识。在这里，我们报告了细胞外聚合物（EPS）的一个先前未被认识的作用，它形成生物膜来保护细胞免受矿物质表面的毒性。与无氧化物对照相比，在氧化物悬浮液中使用菌落平板和 LIVE/DEAD 染色方法，我们发现与具有缺陷生物膜生产能力的同基因敲除突变体相比，铜绿假单胞菌 PAO1 的野生型 EPS 生产菌株具有更高的生存能力。 Oxide toxicity was specific to its surface charge and particle size.高分辨率透射电子显微镜 (HRTEM) 图像和矿物表面高活性氧 (hROS) 的分析表明 EPS 通过物理和化学机制进行屏蔽。 Intriguingly, qualitative as well as quantitative measures of EPS production showed that toxic minerals induced EPS production in bacteria.通过确定具体的毒性机制，我们深入了解矿物表面在促进早期地球细胞表面复杂性（包括 EPS 和生物膜形成）方面的潜在影响。 Key Words: Mineral toxicity—Bacteria—EPS evolution—Biofilms—Cytotoxicity—Silica—Anatase—Alumina.天体生物学 12, 785–798。
Modern ecological niches are teeming with an astonishing diversity of microbial life in biofilms closely associated with mineral surfaces, which highlights the remarkable success of microorganisms in conquering the challenges and capitalizing on the benefits presented by the mineral–water interface. Biofilm formation capability likely evolved on early Earth because biofilms provide crucial cell survival functions. The potential toxicity of mineral surfaces toward cells and the complexities of the mineral–water–cell interface in determining the toxicity mechanisms, however, have not been fully appreciated. Here, we report a previously unrecognized role for extracellular polymeric substances (EPS), which form biofilms in shielding cells against the toxicity of mineral surfaces. Using colony plating and LIVE/DEAD staining methods in oxide suspensions versus oxide-free controls, we found greater viability of wild-type, EPS-producing strains ofPseudomonas aeruginosaPAO1 compared to their isogenic knockout mutant with defective biofilm-producing capacity. Oxide toxicity was specific to its surface charge and particle size. High resolution transmission electron microscopy (HRTEM) images and assays for highly reactive oxygen species (hROS) on mineral surfaces suggested that EPS shield via both physical and chemical mechanisms. Intriguingly, qualitative as well as quantitative measures of EPS production showed that toxic minerals induced EPS production in bacteria. By determining the specific toxicity mechanisms, we provide insight into the potential impact of mineral surfaces in promoting increased complexity of cell surfaces, including EPS and biofilm formation, on early Earth. Key Words: Mineral toxicity—Bacteria—EPS evolution—Biofilms—Cytotoxicity—Silica—Anatase—Alumina. Astrobiology 12, 785–798.