Parallel Microbial Ecology of and Nematode Species in Scottish Soils

spp. are endospore forming bacteria which act as natural antagonists to many of the most economically significant plant parasitic nematodes (PPNs). Highly species-specific nematode suppression may be observed in soils containing a sufficiently high density of spp. spores. This suppression is enacted by the bacteria inhibition of root invasion and sterilization of the nematode host. Molecular methods for the detection of spp. from environmental DNA (eDNA) have been described; however, these methods are limited in both scale and in depth. We report the use of small subunit rRNA gene metabarcoding to profile spp. and nematode communities in parallel. We have investigated spp. population structure in Scottish soils using eDNA from two sources: soil extracted DNA from the second National Soil Inventory of Scotland (NSIS2); and nematode extracted DNA collected from farms in the East Scotland Farm Network (ESFN). We compared the spp. community culture to both nematode community structure and the physiochemical properties of soils. Our results indicate that spp. populations in Scottish soils are broadly dominated by two sequence variants. The first of these aligns with high identity to , a species first described parasitizing , a nematode parasite of woody and perennial plants in northern Europe. The second aligns with a -like sequence which was first recovered from a farm near Edinburgh which was found to contain bacterial feeding nematodes and spp. encumbered by spp. endospores. Further, soil carbon, moisture, bulk density, and pH showed a strong correlation with the spp. community composition. These results indicate that metabarcoding is appropriate for the sensitive, specific, and semi-quantitative profiling of species from eDNA.