Multi-kingdom microbial assemblage modulates its metabolism under contrasted cloud conditions.

Area of Science:

• Atmospheric microbiology
• Environmental microbiology
• Biogeochemistry

Background:

• Microorganisms in clouds influence atmospheric chemistry.
• Environmental factors modulating microbial activity in clouds are poorly understood.

Purpose of the Study:

• To investigate the metabolic and gene expression responses of cloud microbial communities to simulated cloud conditions.
• To elucidate distinct survival strategies of eukaryotic and prokaryotic cloud microbes.

Main Methods:

• Utilized a synthetic cloud water medium with representative microbial isolates (yeast and bacteria).
• Exposed cultures to contrasted conditions: temperature (5°C vs 17°C), light (dark vs. artificial solar light), and hydrogen peroxide (0 μM vs. 250 μM).
• Applied metabolomics and metatranscriptomics to analyze metabolic profiles and gene expression.

Main Results:

• Identified 25 differentially abundant metabolites and 218 differentially expressed genes (DEGs).
• Simulated summer day conditions revealed active mitochondrial energy production in yeast, with DEGs for fatty acid metabolism and succinate assimilation. Bacteria showed DEGs for cell division arrest and reactive oxygen species scavenging.
• Simulated winter night conditions indicated similar growth states for both yeast and bacteria, with DEGs related to translation, protein repair, and cell cycle functions.

Conclusions:

• Cloud microbial communities exhibit distinct metabolic and gene expression strategies in response to environmental variables.
• Eukaryotic and prokaryotic cloud microbes employ different survival mechanisms influenced by temperature, light, and oxidant levels.
• Findings enhance understanding of microbial roles in cloud water and atmospheric chemistry.