Common Actinobacteria and their phages

Actinobacteria of the acI lineage ('Ca. Nanopelagicales') are ubiquitously present and often among the most abundant microbes in freshwater lakes around the globe. While several hypotheses for their success have been advanced based on culture-independent approaches, most remain untested owing to a lack of cultivated representatives. It is thus essential to isolate environment acI strains in order to get a holistic picture of their ecology and role in the ecosystem. Moreover, community manipulation experiments suggested that top-down control of acI through viral lysis might be stronger than through grazers. Using acI cultures, we aim to isolate viruses with clearly specified hosts, identify novel acI viruses and determine host ranges. With additional experimental work, these cultures will help us identify the reasons why acI actinobacteria are so abundant even in the presence of viruses.