Gut eukaryotic disease-discriminatory taxa are indicative of Pacific white shrimp (Litopenaeus vannamei) white feces syndrome

Increasing evidence has revealed a tight association between host diseases and dysbiosis in its gut bacterial communities. However, it remains uncertain whether this interplay also holds true for gut eukaryotes. To fill this knowledge gap, using Illumina sequencing the eukaryotic 18S rRNA genes, we explored the gut eukaryotic signatures of Pacific white shrimp (Litopenaeus vannamei) suffered from white feces syndrome (WFS). The gut eukaryotic communities in WFS shrimp differed significantly (P<.001) from healthy cohorts, accompanied with a significant (P=.016) reduction in diversity. Compared with healthy shrimp, Basidiomycota and Ascomycota were overrepresented, while Desmodesmus and Gymnodiniphycidae were underrepresented in WFS ones. A phylogenetic-based mean nearest taxon distance (MNTD) analysis revealed that WFS significantly (P=.008) shifted ecological processes that govern the gut eukaryotic community from determinism to stochasticity. In addition, WFS shrimp exhibited less connected and cooperative interspecies interactions compared with healthy cohorts. Notably, we identified 14 disease-discriminatory taxa that were indicative of shrimp health statuses, with an overall 96.4% diagnosis accuracy. In addition, the 14 taxa between pre-WFS and corresponding healthy shrimp exhibited same change direction (increased or decreased) with that of WFS, suggesting that the identified disease-discriminatory taxa are not transient and are predictive of WFS onset. Among these, 11 indicators were affiliated with Opisthokonta and Archaeplastida phyla, which conjointly contributed 39.8% dissimilarity in the gut microbiotas between healthy and WFS shrimp, indicating that WFS occurrence could be attributed to dysbiosis of the two phyla. Collectively, our findings provide an integrated overview on the intimate association between WFS and gut eukaryotes. In addition, the gut disease-discriminatory taxa can serve as indicators for quantitatively diagnosing the incidence of shrimp WFS.