Deep shale formations underlie most of North America and are typically inhospitable to microbial life. However, hydrologic fracturing of shale creates space and injects moisture and nutrients into the system, thus allowing new microbial communities to form. These communities can cause problems by corroding infrastructure and souring the hydrocarbon steam. Understanding the behavior of these microbial communities could lead to better management techniques. Recently, researchers examined the microbial genomes and metabolic capacity of fractured shale wells in Oklahoma, USA. Oklahoma shale is much hotter and has lower salinity than the previously characterized formations in the eastern USA. This study found that the Oklahoma formations had greater microbial taxonomic and metabolic diversity than the eastern formations. Sampling over time revealed that this microbial community broke down complex polymers from the fracturing process and used them for nutrients. The samples also contained thousands of viral genomes, suggesting that viral predation plays a key role in the community dynamics of this system. These results suggest that while shale ecosystem community structures are largely shaped by the combination of viral predation and nutrient availability, they are also influenced by physicochemical factors like temperature and salinity.