In the last decade, significant technological achievements have resulted in the widespread use of nanomaterials including NMC (LixNi1/3Mn1/3Co1/3O2), a nanoscale cathode material used Lithium ion batteries. The rapid increase in the use of these materials calls for a better understanding of their impact on human health and the environment. Exposure to engineered nanoparticles has been shown to induce DNA damage in various organisms. Nanoscale NMC has been found to inhibit bacterial oxygen uptake, however the specific cytotoxic mechanisms involved remain unclear. One hypothesis is that nanoscale NMC-induced DNA damage is due to the generation of covalently modified nucleobases (DNA adducts). In this study, we investigated bacterial DNA damage in two environmentally relevant bacterial strains upon NMC exposure through optimization and use of our recently developed DNA adductomic approach. This technique allows the characterization of DNA damage by screening for DNA modifications, beyond the traditionally studied 8-OHdG. Shewanella oneidensis and Bacillus subtilis were exposed to nanoscale NMC. The bacterial DNA was extracted and enzymatically digested with purification by off-line HPLC fraction collection and analysis via nanoLC/MS3 with data dependent scanning and MS3 triggering upon detection of the neutral loss of deoxyribose (-116.0474 Da). Data analysis was carried out using newly in-house developed software. Several DNA modifications were observed to be greater or only present in exposed bacteria in both strains. The mechanisms leading to DNA adducts upon exposure to nanoscale NMC are yet to be elucidated, however the chemical nature of the DNA adducts detected suggests that reactive oxygen species and increased lipid peroxidation are likely involved in the DNA damage process. These findings confirm the ability of our approach to chemically characterize DNA damage induced by nanoscale NMC in bacteria and provide insight to elucidate the responsible chemical mechanisms.

DNA damage as a toxicity mechanism of NMC (LixNi1/3Mn1/3Co1/3O2) nanomaterial to bacteria Shewanella oneidensis MR-1 and Bacillus subtilis

2019 Fall National Meeting

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