10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Modulation and Resilience of the Metabolome of Pseudomonas graminis, a Cloud Bacterium, Facing H2O2 Atmospheric Stress
Nolwenn Wirgot, Marie Lagree, Mounir Traikia, Cyril Jousse, Isabelle Canet, Martine Sancelme, Pierre Amato, Ludovic Besaury, Bernard Lyan, ANNE MARIE DELORT, Université Clermont Auvergne
Abstract Number: 717 Working Group: Bioaerosols
Abstract In cloud waters microorganisms are metabolically active although they are exposed to very strong stresses, especially due to the presence of reactive oxygenated species, including H2O2 and radicals [1,2]. In order to understand how microorganisms can modulate their metabolism facing H2O2 stress [3], we have investigated by a metabolomics approach the response of a Pseudomonas graminis strain, isolated from cloud waters, to hydrogen peroxide exposure. For this purpose P. graminis cells were incubated in microcosms containing artificial cloud waters in the presence or absence of H2O2. Metabolites were extracted at two time points (50 min and 24 h) that were important regarding the evolution of ATP cellular content and H2O2 degradation over time. These bacterial extracts were analyzed by LC-MS and 1H-NMR using the Metabolic Profiler® facility (Bruker). Metabolic profiles were converted into matrices and statistical analyses (PCA, PLS-DA) were performed; key markers of this oxidative stress were identified by 2D NMR and LC-MS-Orbitrap.
At time 50 min, when H2O2 was still present in the incubations, the bacteria adapted and modulated their metabolome facing this stress. The major metabolic pathways of Pseudomonas graminis (13b-3) impacted by the presence of hydrogen peroxide were the carbohydrate pathway, glutathione, energy, lipid and amino-acid metabolisms. Unexpectedly, the concentration of a few dipeptides containing mainly Ala, Val, Leu (Ile) was also highly modified in the presence of H2O2. These dipeptides are reported here for the first time as biomarkers of oxidative stress. Interestingly, at time 24 h, when H2O2 has been completely biodegraded by the cells, no more significant difference was observed between the metabolites of exposed and non-exposed cells to H2O2. This shows the resilience of this bacterium metabolome after H2O2 stress exposure.
These results are discussed in terms of impacts on cloud chemistry.
References
[1] M. Vaïtilingom, L. Deguillaume, V. Vinatier, M. Sancelme, P. Amato, N. Chaumerliac, A.-M Delort, Proceeding of National Academy of Science USA, 110, (2013), 559. [2] M. Joly, P.Amato, M. Sancelme, V. Vinatier, M. Abrantes, L. Deguillaume, A.-M. Delort, Atmospheric Environment, 117, (2015), 92. [3] N. Wirgot, V. Vinatier, L. Deguillaume, M. Sancelme, A.-M. Delort, Atmospheric Chemistry and Physics, 17,(2017) 14841. https://doi.org/10.5194/acp-17-14841-2017.