Fig. 2

Characterization of microbial communities between hosts and Ascaris worms AAscaris microbiome composition is closer to the upper gastrointestinal tract microbiome than to the colon and cecum. Nonmetric multidimensional scaling (NMDS) showing differences in microbial composition among gastrointestinal compartments from infected individuals: duodenum, jejunum and ileum (upper GI tract), cecum and colon (lower GI tract), and Ascaris worms. Each triangle in the graph represents an infected individual, circles represent individual Ascaris, and distances between points are proportional to their biological dissimilarity, calculated with the Bray-Curtis index. The color of the points and the dotted lines surrounding them represents the clusters by compartment. NMDS shows general proximity among Ascaris microbiomes and those from upper GI tract compartments, particularly to jejunum and duodenum, the jejunum being the distinct site of infection. Arrows represent the top ASVs (genus level) linked to NMDS axes; their length reflects the relative importance of the ASV on the respective axes. B Host and parasite microbiome compositions are closer when both come from the same individual and the infection site. Dissimilarity among bacterial communities derived from Ascaris to those from the infected hosts is shown. Host and parasite microbiomes were significantly more similar when they came from the same host individual (LRT: χ² = 52.349, df = 1, p < 0.001; left). Microbiomes from the shared gut compartment (host microbiomes from the jejunum and those of Ascaris) are only more similar when they additionally come from the same host individual (LRT: χ² = 33.821, df = 1, p < 0.001; right). If the host individual was not taken into account, only the kind of compartment (jejunum) did not significantly explain microbiome similarity (LRT: χ² = 0.441, df = 1, p = 0.507; middle). The dashed line highlights that the median microbial dissimilarity in host-parasite microbiomes from different individual, different compartment, and different individual and compartment is above 0.75. C The majority of Ascaris microbiomes are similar to their host’s jejunum microbiome. Bray-Curtis dissimilarity values to assess the similarity between worms within the same hosts. In six out of eight pigs, the jejunum-Ascaris microbial dissimilarity has a median below the overall median of host-parasite dissimilarity (0.75; dashed line). This is a graphical representation of the significantly higher similarity between host-parasite pairs from the same host than host-parasite pairs from different hosts (GLMM; Table 2). This also points to residual variability in the similarities, so that (only) few worms’ microbiomes are still less similar to their own hosts microbiome than to that of the other hosts. The closer the values are to zero, the more similar the microbiome compositions