School of Materials Science & Engineering, Nanyang Technological University, Block N3.1-B3a-02, 50 Nanyang Avenue, Singapore, 639798, Singapore.
Avram and Stella Goldstein-Goren, Department of Biotechnology Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 84105, Beer-Sheva, Israel.
Environ Sci Pollut Res Int. 2018 Feb;25(5):5003-5012. doi: 10.1007/s11356-017-0782-8. Epub 2017 Dec 5.
Carbon nanotubes (CNTs) have emerged recently as superior adsorbent materials for the removal of recalcitrant pollutants. The potential of combining the sorption capability of CNTs with bacterial degradation for pollutant removal, however, necessitates further investigation of the mechanisms of CNTs' toxicity towards bacterial cells. In this study, we used a panel of stress-responsive recombinant Escherichia coli bioluminescence bacterial strains to explore the possible mechanisms of toxicity of multiwalled carbon nanotubes (MWCNTs). The effects of MWCNTs on markers of oxidative stress, protein, DNA, and membrane damage enabled the exposition of some of the mechanisms of their antimicrobial properties. Using both a bioluminescence bioreporter panel and live/dead staining, we observed that membrane damage played a role in the toxicity of MWCNTs. A subsequent viability study using three strains of bacteria-two gram-negative (Escherichia coli, Pseudomonas aeruginosa) and one gram-positive (Bacillus subtilis)-showed significant MWCNT toxicity in hypotonic water and phosphate-buffered saline solution, compared with the MWCNT toxicity towards the same bacteria incubated in isotonic-rich media. Using a field-emission scanning electron microscope, we demonstrated that membrane damage is caused largely by MWCNTs trapping bacteria and piercing the cell walls. As a result of our observations, we propose integrating MWCNTs and bacteria degradation for pollutant removal in nutrient-rich media to minimize the toxicity effect of CNTs.
碳纳米管（CNTs）作为去除难降解污染物的优异吸附材料最近引起了关注。然而，为了将 CNTs 的吸附能力与细菌降解结合用于污染物去除，需要进一步研究 CNTs 对细菌细胞毒性的机制。在本研究中，我们使用了一组应激反应重组大肠杆菌生物发光细菌菌株来探索多壁碳纳米管（MWCNTs）毒性的可能机制。MWCNTs 对氧化应激标志物、蛋白质、DNA 和膜损伤的影响揭示了其抗菌特性的一些机制。使用生物发光生物报告基因和活/死染色，我们观察到膜损伤在 MWCNTs 的毒性中起作用。随后使用三种细菌（两种革兰氏阴性菌[大肠杆菌、铜绿假单胞菌]和一种革兰氏阳性菌[枯草芽孢杆菌]）进行的生存能力研究表明，与在等渗丰富培养基中孵育的相同细菌相比，MWCNTs 在低渗水中和磷酸盐缓冲盐溶液中对细菌具有显著的毒性。使用场发射扫描电子显微镜，我们证明了膜损伤主要是由 MWCNTs 捕获细菌并刺穿细胞壁引起的。根据我们的观察结果，我们建议在富含营养的培养基中整合 MWCNTs 和细菌降解以最小化 CNTs 的毒性效应。
