REACT New infrastructure to analyze microbial-cloud interactions as a key contributor to climate change mitigation (Microbial Aerosol Cloud - FacilitY MAC-Y) [funded by EU]

Project staff:

Prof. Dr. Jörg Bendix
Dr. Leslie Ann Kremper


Research partner:

Prof. Dr. Anke Becker, SYNMIKRO,

Prof. Dr. Tobias Erb, MPI Terrestrische Mikrobiologie,


Bacterial aerosols are playing an increasingly important role in environmental research. They serve as condensation nuclei (CCN) for cloud droplets, thereby increasing their lifetime in the atmosphere and can thus be exchanged between ecosystems via droplet deposition and precipitation. Their interaction with cloud formation thus has significance for atmospheric, ecosystem, and health research. The aim of the project is to systematically characterize bacteria of low stratiform clouds with respect to their CCN-relevant properties using the new infrastructure MAC-Y (Microbial Aerosol Cloud - FacilitY) . The planned experiments will be used to create a parameter set for numerical cloud models, a key component of weather and climate models. The methodological access includes the collection of water from near-ground clouds with a specially designed cloud water sampler, sequencing of the water samples to determine the cloud microbiome, culturing of identified bacterial species, their aerosolization with the MAC-Y aerosol processing unit, and determination of their CCN activation to cloud droplets with the specially designed MAC-Y microbial CCN counter (MCCNC). The expected outcomes are a tested and optimized experimental chain as a starting point for further research activities on the cloud microbiome, and a comprehensive database of bacterial CCN properties of ground-level clouds for parameterization of cloud models. With the help of the experimentally determined activation rates, comprehensive cloud model studies are carried out in order to record the influence of atmospheric microbes on climate change. The resulting improved climate models will be able to better represent future climate conditions for the derivation of climate and environmental protection measures.

MAC Y experimental scheme - (1) collection cloud water, (2) sequencing and culturing bacteria, (3) aerosolization, (4) size selection, (5) classification of aerosol and determination of volume equivalent diameter of bacteria, (6) activation at different saturations, (7) rate of bacteria activated to droplets, (8) transfer of characteristic values as the activation rate to a database.



Operation scheme MAC Y


Dieses Projekt wird aus Mitteln des Europäischen Sozialfonds als Teil der Reaktion der Union auf die COVID-19-Pandemie finanziert.

Verantwortet wird die hessische Initiative durch das Hessische Ministerium für Soziales und Integration.

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