Microbial interactions within single cell genomes of uncultured protists

We generated genome data from three individual Picobiliphyta cells isolated from a seawater sample off Maine, USA. In contrast to the recent description of this lineage, we found no evidence of plastid DNA, suggesting these picobiliphytes are heterotrophs. Genome reads from one cell were dominated by a novel DNA nanovirus widespread in the world’s oceans. A significant fraction of DNA sequences from the other two cells was derived from marine Bacteroidetes and large DNA viruses, likely protist food sources. Our work uncovered remarkably dynamic biotic interactions among marine microorganisms without biases introduced by cultivation.