Abstract Hydrogen peroxide plays a central role in atmospheric chemistry as a precursor of HO• radicals and determines the oxidant capacity of the liquid phase [1]. In cloud water, H2O2 is also in direct interaction with microorganisms which are metabolically active and can have a significant impact on the oxidant capacity [2]. In this context, the present work highlights the interactions between H2O2 and cloud microorganisms.
First, experiments were performed with model strains isolated from clouds in microcosms designed to mimic the cloud environment, including the presence of light and iron. The most important result was that H2O2 strongly impacted the microbial energetic state as shown by ATP measurements in the presence and absence of H2O2. This ATP depletion was not related to the loss of cell viability.
Secondly, correlation studies were done based on real cloud measurements from 37 clouds samples collected at the puy de Dôme station (1465 m., France). The results supported a strong correlation between ATP and H2O2 concentrations and confirmed that H2O2 modulates the energetic metabolism of the cloud microbiome. This modulation could impact cloud chemistry.
Acknowledgements
N. Wirgot is a recipient of a PhD fellowship from the MESR (French government).
Part of this work was supported by the French ANR program BIOCAP. The authors are very grateful to the OPGC staff for collecting the cloud samples at the puy de Dôme station wwwobs.univ-bpclermont.fr/SO/beam/index.php.
References
[1] D. Vione et al., Annali Di Chimica, 2003, 93, 477–488 [2] M. Vaïtilingom, et al , PNAS, 2013, 110, 559–564.