Insights into the dynamics and evolution of Rummeliibacillus stabekisii prophages in extreme environments: from Antarctic soil to spacecraft floors

Since prophages can play a multifaceted role in bacterial evolution, this study aims to characterize the virome of Rummeliibacillus stabekisii, a bacterium isolated from different environments, including Antarctic soil and NASA spacecraft floors. From the analyses, it was found that the Antarctic strain, PP9, had the largest number of prophages, including intact ones, indicating potential benefits for survival in adverse conditions. In contrast, other strains harbored predominantly degenerate prophages, suggesting a dynamic process of gene gain and loss during evolution. Furthermore, strain PP9 exhibited polylysogeny, a strategy capable of increasing its competitive advantage by providing a broader spectrum of defensive mechanisms. In addition, evidence demonstrates that prophage regions in PP9 act as hotspots for recombination events, favoring the insertion of different phages and possible antimicrobial resistance genes. Finally, lytic cycle induction experiments revealed at least two intact prophages active in PP9. In this way, understanding the interaction between viruses and bacteria can provide valuable information about microbial evolution and adaptation in extreme environments, such as Antarctica.