Metagenomic Biodiversity of Giant Viruses and Virophages in the North Sea    

Viruses are highly abundant in ocean environments and play a crucial role in marine ecosystems. Despite their significance, the field of marine virus research is relatively new, with only about 30 years of establishment. Viruses outnumber bacteria by approximately tenfold in sea surface water, with about 10^8 marine viruses per mL-1. These viruses have a direct impact on the biogeochemical cycle by releasing dissolved organic matter through lysis, which becomes available to other organisms. Although environmental viruses possess the greatest genetic diversity on Earth, their understanding is still limited. Recent studies have accumulated a significant amount of marine virome sequences; however, only a fraction of these sequences are available in public databases. Consequently, there is a need for further research to characterize and sequence marine viruses. This thesis aims to address this gap by identifying giant viruses and virophages in the central North Sea.