Persistent Desert Microbiota in the Southern European Sky

Area of Science:

• Microbiology
• Atmospheric Science
• Ecology

Background:

• Aerobiology traditionally focused on lower atmospheric layers, assuming local ecosystem control over airborne microbes.
• Limited understanding of long-range microbial dispersal and its impact on distant ecosystems.

Purpose of the Study:

• To investigate the long-term influence of North African desert microorganisms on Southern European ecosystems via atmospheric transport.
• To identify factors governing the long-range dispersal and persistence of airborne microbial communities.

Main Methods:

• Temporal aerosol sampling in the free troposphere over nearly three decades.
• Analysis of high-troposphere air mass origins and topsoil microbial genetic data from North Africa.
• Comparison with a global bacterial database and examination of rainfall samples.

Main Results:

• Demonstrated a persistent influence of North African desert microbes in Southern Europe, even in rain originating from the Atlantic.
• Identified dust outbreak frequency, altitude, and residence time as key factors for microbial dispersal and persistence.
• Showcased the widespread presence of desert microorganisms despite the dominance of sea spray in global aerosol emissions.

Conclusions:

• Atmospheric microorganisms exhibit a significant and enduring connection with terrestrial ecosystems.
• Long-range atmospheric transport plays a critical role in global microbial dispersal and ecosystem functioning.
• Further research is needed to explore intercontinental microbial exchange with deserts and drylands globally.