Resumen de la plática

Viruses and virus-like genetic elements are associated with all life on Earth. They have had major roles in the evolution of cellular life as we know it, having triggered significant biological innovations that stimulated the rise of microbial and complex life. In modern environments, viral infection is a major modulator of bacterial community composition and metabolism. Yet the potential role of viruses in modulating the production of bacterial biosignatures preserved in the geologic record remains largely unknown. In this talk, I will discuss recent advances in understanding the impact of viruses on biosignatures in euxinic lakes that are analogs of Proterozoic oceans. In these lakes, green and purple sulfur bacteria (GSB and PSB) are the main primary producers, coupling carbon fixation with sulfur oxidation. We show that viral infection strategies are coupled with GSB and PSB activity on these lakes, where PSB are predominantly infected by viruses that establish dormant, long-term interactions, and GSB are infected by lytic viruses that cause cell death. These viruses encode genes that can affect metabolic pathways involved in carbon fixation, sulfur utilization, and photosynthetic pigment production. One photosynthesis-related gene was the most highly transcribed viral gene in one of the studied lakes, coinciding with the detection of oxidized forms of photosynthetic pigments that can be preserved in sediments and potentially in the geologic record over long timescales. These results provide the first evidence of viral impacts on bacterial metabolisms that could be detected in the geological record, opening the doors to investigating ancient infections that may have shaped life-Earth coevolution.

Cynthia Silveira. College of Science and Arts, Department of Biology, University of Miami, USA
https://people.miami.edu/profile/76b6138029a46082d24c567a640601e0

Frontiers in Genomics