The microbiome associated with Trichodorus primitivus is enriched with Janthinobacterium compared to soil

Although soil biota mediates many key processes that deliver multiple environmental benefits, interactions between soil biota are not well characterized. In an ecological context, studies to date on the associations between nematodes and bacteria have mostly focused on either intracellular bacteria or bacteria that have a potential role in crop pathogenesis by endoparasitic nematode species, that is, those species that have a component of their life cycle within the plant host. Moreover, evolutionary studies have utilized the model nematode species, Caenorhabditis elegans, for studies on survival, behavior, and fecundity. In this study, we characterize the bacterial communities associated with an ectoparasitic nematode species, Trichodorus primitivus, whose complete life cycle is external to the plant host. Compared to the soil from which the nematodes were extracted, the diversity of bacterial communities associated with T. primitivus was reduced. By contrast, the nematode-associated bacterial community was significantly enriched with Janthinobacterium, a known antagonist of soilborne pathogens. This study advances knowledge on the interactions between bacteria and ectoparasitic nematodes, which could help inform the future development of novel strategies for nematode control.