Nematodes Vector Bacteriophages in Spatially Structured Habitats

Samenvatting

Bacteriophages (phages) infect bacteria and are likely a major driver of nutrient and carbon cycling in soils. However, to infect

new hosts, phages need to travel through the soil, overcoming a diverse range of spatial and physical barriers without the benefit

of active motility or sensory perception. Pioneering evidence in laboratory settings showed that phages may hitchhike on motile

organisms, including nematodes. Here, we tested whether nematodes also vector phages through the hostile soil labyrinth. First,

we demonstrated that Caenorhabditis elegans transferred the laboratory model phage T7 and the soil phage Φ ppu-W11 on agar.

Second, we confirmed that two mechanisms contribute to phage transfer: intestinal intake and cuticular attachment. Presence of

host bacteria was not necessary for phage vectoring by nematodes. Finally, phage vectoring by Caenorhabditis nematodes was

tested in microcosms containing compost and sandy soil. In these spatially and physically complex habitats, nematodes were

critical for moving phages. Together, these experiments demonstrate a previously unknown mechanism for interactions between

nematodes and phages within the soil microbiome.