# The Microbiome Within a Microbe: Rethinking Blastocystis Biology

## TL;DR

This paper suggests that Blastocystis, a common gut microbe, might host its own internal microbiome, changing how we understand its role in gut health.

## Contribution

The paper proposes a novel view of Blastocystis as a potential 'microbiome within a microbe' and suggests modern methods to test this idea.

## Key findings

- Old observations of bacterial- and viral-like particles in Blastocystis may be significant and not random.
- Comparisons to other protozoa suggest such internal microbes could influence Blastocystis's biology and interactions.
- Modern techniques like organ-on-a-chip and single-cell multi-omics are proposed to study this hypothesis.

## Abstract

Blastocystis spp., one of the most prevalent microeukaryotes in the human gut, has long puzzled researchers with its ambiguous role in health and disease. Decades‐old microscopy studies reported bacterial‐ and viral‐like particles within Blastocystis spp. cells, but these findings have been mainly overlooked. Comparable associations in other protozoa, such as those between Trichomonas vaginalis and Mycoplasma, as well as protozoan–virus interactions, are known to influence metabolism, immune evasion, and ecological fitness. Here, we revisit these neglected observations in Blastocystis spp., framing them within the holobiont concept and proposing that this protist may host its own microbial consortium. We also propose potential mechanisms, ecological implications, and modern experimental strategies—from organ‐on‐a‐chip to single‐cell multi‐omics—to rigorously test this hypothesis. Recognizing Blastocystis spp. as a possible “microbiome within a microbe” could transform our understanding of its biology and its place in gut microbial ecology.