Siderophores in Cloud Waters and Potential Impact on Atmospheric Chemistry: Production by Microorganisms Isolated at the Puy de Dôme Station

• DOI: 10.1021/acs.est.6b02335
• Publication Date: 2016-08-01T17:27:57Z
• Authors: Virginie Vinatier; Nolwenn Wirgot; Muriel Joly; Martine Sancelme; Magali Abrantes; Laurent Deguillaume; Anne-Marie Delort
• Keywords: 13. Climate action; Iron; Pseudomonas; [CHIM] Chemical Sciences; [CHIM]Chemical Sciences; Siderophores; Iron Chelating Agents; Ferric Compounds; 01 natural sciences; 6. Clean water; 0105 earth and related environmental sciences

A total of 450 bacteria and yeast strains isolated from cloud waters sampled at the puy de Dôme station in France (1465 m) were screened for their ability to produce siderophores. To achieve this, a high-throughput method in 96-well plates was adapted from the CAS (chrome azurol S) method. Notably, 42% of the isolates were siderophore producers. This production was examined according to the phyla of the tested strains and the type of chelating functional groups (i.e., hydroxamate, catechol, and mixed type). The most active bacteria in the clouds belong to the γ-Proteobacteria class, among which the Pseudomonas genus is the most frequently encountered. γ-Proteobacteria are produced in the majority of mixed function siderophores, such as pyoverdines, which bear a photoactive group. Finally, siderophore production was shown to vary with the origin of the air masses. The organic speciation of iron remains largely unknown in warm clouds. Our results suggest that siderophores could partly chelate Fe(III) in cloud waters and thus potentially impact the chemistry of the atmospheric aqueous phase.