Abstract
Nematodes often engage with diverse pathogens. Prior research has unveiled nematode-specific
microsporidia and fungus-related obligate intracellular pathogens with both terrestrial and marine
nematodes across the United States and select European countries. However, our comprehension of
microsporidia diversity infecting nematodes in Asia, particularly Japan, remains limited. This study
aimed to delve into the diversity of microsporidia-infecting nematodes and unearth novel interactions
by investigating wild-isolated bacterivorous and fungivorous nematodes in Japan. Our investigation,
successfully isolated 12 strains of microsporidia, among them an unidentified species (MKI37), from
bacterivorous nematodes. Notably, MKI37 was found to infect Distolabrellus veechi, a nematode
species previously unrecognized as a host for microsporidia. Intriguingly, no infections were detected
in fungivorous nematodes. Our findings suggest a more pronounced diversity of microsporidia-infected
nematodes among bacterivorous nematodes.
