Blastocystis and gut microbiota

Colonization with the enteric protozoa Blastocystis is associated with increased diversity of human gut bacterial microbiota, Christophe Audebert, Gaël Even, Amandine Cian, The Blastocystis Investigation Group, Alexandre Loywick, Sophie Merlin, Eric Viscogliosi & Magali Chabé

Scientific Reports 6, Article number: 25255 (2016) :

Digestive systemAbstract :

Alterations in the composition of commensal bacterial populations, a phenomenon known as dysbiosis, are linked to multiple gastrointestinal disorders, such as inflammatory bowel disease and irritable bowel syndrome, or to infections by diverse enteric pathogens. Blastocystis is one of the most common single-celled eukaryotes detected in human faecal samples. However, the clinical significance of this widespread colonization remains unclear, and its pathogenic potential is controversial. To address the issue of Blastocystis pathogenicity, we investigated the impact of colonization by this protist on the composition of the human gut microbiota. For that purpose, we conducted a cross-sectional study including 48 Blastocystis-colonized patients and 48 Blastocystis-free subjects and performed an Ion Torrent 16S rDNA gene sequencing to decipher the Blastocystis-associated gut microbiota. Here, we report a higher bacterial diversity in faecal microbiota of Blastocystis colonized patients, a higher abundance of Clostridia as well as a lower abundance of Enterobacteriaceae. Our results contribute to suggesting that Blastocystis colonization is usually associated with a healthy gut microbiota, rather than with gut dysbiosis generally observed in metabolic or infectious inflammatory diseases of the lower gastrointestinal tract.


Boxplots of observed OTUs richness and Shannon diversity indexes distinguishing between patients colonized or not by Blastocystis.

Method for reads production :

– Amplification of sequence regions of the 16S rRNA gene (V3–V5 variable regions) using the forward primer For16S_519, CAGCMGCCGCGGTAATAC and
the reverse primer Rev16S_926, CCGTCAATTCMTTTGAGTTT.
– Sequencing of the 96-barcoded bidirectional library through PGM, Ion Torrent (Life Technologies) with the Ion 318™ Chip and Ion PGM™ 400 Sequencing Kit (Life Technologies).
Method for reads analysis :
– Homemade pipeline used for the primary analysis of Ion Torrent sequencing data: from FastQ files to the BIOM file


icon_downloadOTU count tables and normalized global BIOM file are available for download.


Homemade scripts in above pipeline are available for download.

Reads are available : link to SRA (Short Reads Archive)


Vacuolar forms in culture studies of Blastocystis: phase-contrast (A) and DIC (B) microscopy. Vacuolar forms of Blastocystis in stool smears: Giemsa (C) and Para -Selles Kop -Color – Fumouze® MIF ( Merthiolate formaldehyde and lugol ) (D).The scale bar is 10 µm. From: Parasitologie Blastocystis, Les Feuillets de Biologie, n°331, Juillet 2016.