Lang-Yona, N. | Search bioRxiv

bioRxiv2026

Virus-host interactions and viral population dynamics across atmospheric cloud events

BackgroundCloud water harbors diverse microbial communities despite its extreme oligotrophic conditions. However, the ecological and evolutionary dynamics of viruses in these transient atmospheric habitats remain poorly understood. Clouds have traditionally been regarded primarily as passive carriers of microorganisms rather than as active ecological environments supporting microbial interactions. In this study, cloud water was sampled at Mount Verde, Cape Verde Islands (744 m a.s.l.). We performed metagenomic analyses of iron-flocculated cloud water alongside genome analyses of a bacterial isolate and metagenome-assembled genomes using established bioinformatic approaches. Viral diversity, virus-host interactions, metabolic functions, genetic adaptations, and viral population dynamics across cloud events were investigated. In addition, UV-B resistance experiments were conducted for a novel cloud-water isolate. ResultsWe isolated 24 cloud water bacteria, including four novel species lineages, and recovered 62 high-quality metagenome-assembled genomes, including 10 novel species lineages. We identified 458 viral operational taxonomic units and 237 virus-host linkages across diverse prokaryotic hosts, revealing active viral predation across diverse bacterial taxa. In addition, CRISPR spacer matches from isolates of novel bacterial lineages such as Deinococcus nubigenus MPC36 were found. Viruses carried genes involved in host adaptation to environmental stressors, including cold-shock response, UV radiation resistance, and osmotic stress. In addition, viral populations exhibited SNP-level microdiversity and shifts in single-nucleotide variant composition across temporally proximate cloud events, indicating rapid population turnover. Experimental characterization of the cloud isolate Curtobacterium nubigenum MPC39 further revealed pronounced resistance to UV-B radiation and the presence of an inducible prophage, Curtobacterium phage vB_CnuS_Cirrus1 assigned to the new viral family Nebulaviridae, which could be validated in transmission electron microscopy. Reconstructed genomes from cloud-associated bacteria encoded carbon monoxide dehydrogenase genes and UV resistance genes, suggesting trace gas metabolism and enhanced UV protection as survival strategies in oligotrophic cloud droplets. In silico replication rates estimated using iRep were consistent with active bacterial replication at the time of sampling. ConclusionsTogether, these findings demonstrate that clouds are not merely passive carriers of microorganisms, but dynamic atmospheric ecosystems in which virus-host interactions shape microbial diversity and contribute to microbial turnover, atmospheric dispersal, and cloud-water biogeochemistry.

microbiology↗

bioRxiv2024

Biofilm Formation and Niche Adaptation Play Fundamental Role in Shaping Long-Distance Transported Dust Microbial Community

The long-distance transport of microorganisms via dust events is expected to become more prominent and intensified. At the same time, the survival mechanisms of air/dust-borne bacteria and their possible contribution to global processes remain poorly understood. In this study, we characterized Bacillus species from transitional season dust storms, previously identified as a significant component of the bioactive community of the dust microbiome. Our results demonstrated substantial growth and biofilm formation diversification, potentially linked to niche adaptation and surface-associated biofilm formation within heterogeneous dust particles. Most dust isolates form biofilms while exhibiting different preferences for media composition. Sterile dust induced biofilm formation, growth, matrix gene expression of B. subtilis, and robust biofilms in key related dust isolates. Overall, our results highlight the significance of biofilm formation as an adaptive mechanism in the distinct habitat of dust storms, with niche adaptation potentially playing a role in microenvironments within the dust particle. These results hold significant potential for implications on terrestrial and aquatic ecology and health, suggesting a pivotal process by which bacteria survive and evolve in this understudied habitat.

microbiology↗

bioRxiv2021

Airborne bacteria over oceans shed light on global biogeodiversity patterns

Microbes are ubiquitous in the oceans and the atmosphere, playing essential roles in biogeochemical processes. The bio-exchanges between the two environments can provide important insights into microbial distribution and diversity but are still not well understood. We simultaneously surveyed the genomic diversity of airborne and marine bacterial communities across 15 000 kilometers in the Atlantic and Pacific oceans. Higher variability of microbial community composition was observed in the atmosphere than in the ocean surface waters. In addition, a greater similarity was observed between oceans than their overlaying atmosphere, and between atmospheric samples than with the ocean beneath. We additionally detected a higher coverage rate and relative abundance of marine bacteria in the Pacific atmosphere as compared to the Atlantic, while the dominant fraction in the Atlantic atmosphere was annotated as soil-associated bacteria. This study advances our understanding of microbial dispersion in the ocean, the atmosphere, and the exchange between them, as well as their potential impact on microbial composition, ecology, and biogeochemistry.

ecology↗