The persistence of DNA from microorganisms exposed to various concentrations of SiO2 (ranging from 0 to 3000 p.p.m.) was monitored over time. The impact of silica mineralization or silicification on the longevity of 16S rRNA and 16 s rDNA genes from whole cells of Bacillus subtilis and Escherichia coli K12 was quantified using real-time polymerase chain reaction (RT-PCR), and cells were visualized using optical microscopy. For B. subtilis, DNA longevity decreased in experiments with higher levels of SiO2 (1000 and 3000 p.p.m.), in comparison to zero or low (100 p.p.m.) levels. For B. subtilis, cell viability was greatest in the absence of silica, and markedly decreased in the presence of any concentration of silica. Survival of Escherichia coli cells, on the other hand, was not sensitive to silica in the solution. All cells died at similar rates over the 180 days they were monitored, decreasing to about 1% survival. DNA longevity for E. coli did appear to be enhanced to some degree by the presence of 1000 p.p.m. silica, but higher or lower concentrations showed no increased longevity in comparison to the no-silica control. Overall, findings of this study do not support the hypothesis that siliceous environments provide enhanced protection and preservation of DNA over time. However, results of this study do provide guidelines on the persistence of DNA that might be expected in modern silica-rich environments, which may be an important factor for proper characterization of present-day microbial communities.

中文翻译：

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暴露于二氧化硅的微生物的DNA持久性：一项实验研究。

随时间监测来自暴露于各种浓度SiO2（范围为0至3000 ppm）的微生物的DNA持久性。使用实时聚合酶链反应（RT-PCR）量化了二氧化硅矿化或硅化作用对枯草芽孢杆菌和大肠杆菌K12全细胞中16S rRNA和16 s rDNA基因寿命的影响，并使用光学显微镜对细胞进行了可视化。对于枯草芽孢杆菌，与零或低（100 ppm）水平相比，在较高SiO2水平（1000和3000 ppm）的实验中，DNA寿命降低。对于枯草芽孢杆菌，在没有二氧化硅的情况下细胞活力最大，而在任何浓度的二氧化硅的存在下细胞活力显着降低。另一方面，大肠杆菌细胞的存活对溶液中的二氧化硅不敏感。在监测的所有180天内，所有细胞均以相似的速率死亡，存活率降低至约1％。1000 ppm二氧化硅的存在确实使大肠杆菌的DNA寿命有所提高，但与无二氧化硅的对照组相比，较高或较低的浓度均未显示其寿命增加。总的来说，这项研究的结果不支持硅质环境随着时间的推移会增强DNA的保护和保存这一假设。但是，这项研究的结果确实提供了在富含二氧化硅的现代环境中预期的DNA持久性的指导原则，这可能是正确表征当今微生物群落的重要因素。1000 ppm二氧化硅的存在确实使大肠杆菌得到了某种程度的增强，但是与无二氧化硅的对照组相比，较高或较低的浓度都没有显示出更长的寿命。总的来说，这项研究的结果不支持硅质环境随着时间的推移会增强DNA的保护和保存这一假设。但是，这项研究的结果确实提供了在富含二氧化硅的现代环境中预期的DNA持久性的指导原则，这可能是正确表征当今微生物群落的重要因素。1000 ppm二氧化硅的存在确实使大肠杆菌得到了某种程度的增强，但是与无二氧化硅的对照组相比，较高或较低的浓度都没有显示出更长的寿命。总的来说，这项研究的结果不支持硅质环境随着时间的推移会增强DNA的保护和保存这一假设。但是，这项研究的结果确实提供了在富含二氧化硅的现代环境中预期的DNA持久性的指导原则，这可能是正确表征当今微生物群落的重要因素。