Evolutionary clues in hot springs

Biotechnology applications can take advantage of microbial organisms to degrade pollutants or produce certain kinds of foods such as yoghurt and bread. Methane-producing bacteria – known as methanogens – are also utilised in sewage-treatment plants but their activity is often hampered by viral infections.

Scientists on the EU-funded (MICVIRECOLHOTSPRINGS) project studied microbial populations to understand the processes of microbial diversity and viral defence. They applied modern sequencing techniques on microorganisms isolated from the extreme environment of Yellowstone National Park hot springs.

The lithotrophic, literally meaning 'rock-eating', microorganisms found in hot springs depend on hydrogen for energy and were isolated alongside viruses to study their interaction. These microorganisms are also very close to the root of the phylogenetic tree of life and are therefore interesting from an evolutionary perspective.

Experiments were performed in the Obsidian Pool of the Yellowstone National Park where the temperature ranges from 58-66° C and the pH from 5.5-6.0. Slurry experiments enabled researchers to obtain microbial isolates for subsequent genomic analyses.

Sequencing the DNA of the methane-producing microbes provided invaluable information regarding their evolution and interaction with other species. Interestingly, microbial genomes were found to contain sequences implicated in antiviral defence. Metagenomic analyses of viruses from the same environment provided additional information regarding their impact on the genetic profile of their host communities. Taken together, this data shows the potential impact that viruses have on the variation of the methanogen gene sequences during evolution.

Given the increasing utilisation of methane-producing microorganisms in biotechnological applications, the project results could significantly improve their output. Most importantly, they offer novel insight into evolution and the role of microbial interactions in driving evolutionary changes.