13-4 Giant DNA Viruses as Drivers of Microbial Community Structure and Biogeochemical Cycling in the Ancient Oasis of Cuatro Cienegas

Session: Earth Life Sciences across the Cordillera

Presenting Author:

Katia Aviña-Padilla

Authors:

Aviña-Padilla, Katia¹, Cadenas-Castrejón, Elizabeth², Guerrero-Flores, Shaday³, González-Sánchez, Antonio⁴, Olmedo-Alvarez, Gabriela⁵, Hernandez-Rosales, Maribel⁶

(1) Cellular Biology, Cinvestav, Mexico City, Mexico City, Mexico, (2) Genetic Engineering, Cinvestav Irapuato, Irapuato, Guanajuato, Mexico, (3) Genetic Engineering, Cinvestav Irapuato, Irapuato, Guanajuato, Mexico, (4) Genetic Engineering, Cinvestav Irapuato, Irapuato, Guanajuato, Mexico, (5) Genetic Engineering, Cinvestav Irapuato, Irapuato, Guanajuato, Mexico, (6) Cinvestav Irapuato, Irapuato, Mexico, ,

Abstract:

Ancient oligotrophic ecosystems provide rare windows into the long-term coupling between microbial life and Earth system processes. Cuatro Ciénegas, an ancient aquatic oasis in northern Mexico, preserves stromatolites and microbial mats that function as living analogs of early marine ecosystems. While microbial diversity and nutrient limitation in this system have been extensively studied, the role of viruses in structuring microbial communities and biogeochemical cycling remains poorly understood.

We performed deep Illumina metagenomic sequencing of a stromatolite and six stratified microbial mat layers to characterize viral diversity and virus–host associations. Taxonomic profiling revealed a diverse and structured virosphere dominated by giant DNA viruses, including Mimiviridae and related genera such as Mimivirus, Megavirus, Moumouvirus, Tupanvirus, among others. Comparative analyses demonstrated strong habitat specificity, with distinct viral assemblages associated with microbial mats versus stromatolites, reflecting contrasts between dynamic and lithified microbial systems.

Virus–host co-occurrence networks revealed strong associations between giant viruses and key bacterial and protist taxa, indicating that viral infection and predation act as major top-down forces regulating microbial community structure. These interactions likely promote microbial turnover, nutrient remineralization, and metabolic coupling under extreme phosphorus limitation. Our results identify giant DNA viruses as active ecological drivers in ancient geomicrobiological systems, linking microbial community organization to biogeochemical cycling over long timescales. By integrating viromics with network-based ecological inference, this study expands Earth system perspectives to include viral processes, offering new insights into ecosystem resilience, microbial evolution, and early Earth analog environments.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

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