Parasites, Drugs and Captivity: Blastocystis-Microbiome Associations in Captive Water Voles

SIMPLE SUMMARY: The last decade has seen a large increase into research on the microbiome and its roles in health and disease. The majority of this work has focused primarily on the bacterial component of the microbiome. However, there is evidence to suggest that microbial eukaryotes colonising the gastrointestinal tract may have roles in the shaping and structuring of the microbiota and are thus likely to influence disease outcomes and host health. The aim of this study was to investigate the questionable pathogen Blastocystis and expand the number of studies on non-primate hosts, which address its associations with bacterial communities in the gut. Herein we examined the bacterial gut microbiota of Blastocystis positive and negative water voles. Results demonstrate no association of Blastocystis, bacterial richness and community composition. Nonetheless, the abundance of some taxa was affected in Blastocystis positive samples. The lack of significant shifts in community abundance between Blastocystis carriers and non-carriers indicates that this microbe may not be having a profound impact on bacterial communities in the gut of these animals. ABSTRACT: (1) Background: Blastocystis is a microbial eukaryote inhabiting the gastrointestinal tract of a broad range of animals including humans. Several studies have shown that the organism is associated with specific microbial profiles and bacterial taxa that have been deemed beneficial to intestinal and overall health. Nonetheless, these studies are focused almost exclusively on humans, while there is no similar information on other animals. (2) Methods: Using a combination of conventional PCR, cloning and sequencing, we investigated presence of Blastocystis along with Giardia and Cryptosporidium in 16 captive water voles sampled twice from a wildlife park. We also characterised their bacterial gut communities. (3) Results: Overall, alpha and beta diversities between water voles with and without Blastocystis did not differ significantly. Differences were noted only on individual taxa with Treponema and Kineothrix being significantly reduced in Blastocystis positive water voles. Grouping according to antiprotozoal treatment and presence of other protists did not reveal any differences in the bacterial community composition either. (4) Conclusion: Unlike human investigations, Blastocystis does not seem to be associated with specific gut microbial profiles in water voles.