Viral communities of porcelana hot springs: Characterization and ecological function

Viruses are ubiquitous in all environments and hot-springs are not the exception even though its extreme conditions. Phototrophic mats of terrestrial hot-springs have been used for decades as models for understanding the composition, structure, and function of microbial communities in nature. Therefore, they provide a theoretical framework in which to study the viral component of these communities.

In this thesis, our main aim was to characterize the structure, activity, lifestyle, and putative host of the thermophilic viral communities and compare them at a local and global scale. In particular, we studied the lytic and lysogenic viral communities of phototrophic microbial mats in two Chilean Patagonia hot-springs (Porcelana and Cahuelmó).

Our results showed that these viral communities are dominated by Caudovirales order being cyanophages the most active group. The viral communities are also genetically diverse, and structured in a classic log-normal distribution, dominated by approximately 21 genotypes out of more than 800 detected. Our evidence, suggest that viruses exert an impact on their hosts by lytic-interactions that stimulate the coevolution of the most active and abundant host-virus pairs such as the cyanobacteria (genus Fischerella) and cyanophages (Podoviridae family). On the other hand, lysogenic-interactions influence the fitness of heterotrophic hosts such as Proteobacteria and Firmicutes, through lysogenic conversion.

Lastly, we propose that hot-spring viruses followed a biogeographic pattern in which the viruses are passively transported by air on a local and global scale, but then locally structured influenced by environmental conditions (pH and temperature) that primarily affect the structure of the host community.

• Nombre: Sergio Guajardo Leiva
• Laboratorio: Ecología Microbiana y Microbiología Ambiental
• Mención: Genética Molecular y Microbiología
• Director Tesis: Beatriz Díez