Widespread consumption of the common food additive xanthan gum by the human gut microbiota

• Published in: Nature microbiology Vol. 7; no. 4; pp. 556 - 569
• Main Authors: Ostrowski, Matthew P., La Rosa, Sabina Leanti, Kunath, Benoit J., Robertson, Andrew, Pereira, Gabriel, Hagen, Live H., Varghese, Neha J., Qiu, Ling, Yao, Tianming, Flint, Gabrielle, Li, James, McDonald, Sean, Buttner, Duna, Pudlo, Nicholas A., Schnizlein, Matthew K., Young, Vincent B., Brumer, Harry, Schmidt, Thomas, Terrapon, Nicolas, Lombard, Vincent, Henrissat, Bernard, Hamaker, Bruce, Eloe-Fadrosh, Emiley A, Tripathi, Ashootosh, Pope, Phillip B., Martens, Eric
• Format: Journal Article
• Language: English
• Published: 01-04-2022
• ISSN: 2058-5276
• DOI: 10.1038/s41564-022-01093-0

The diets of industrialized countries reflect the increasing use of processed foods, often with the inclusion of novel food additives. Xanthan gum is a complex polysaccharide with unique rheological properties that have established its use as a widespread stabilizer and thickening agent. Xanthan gum’s chemical structure is distinct from the host and dietary polysaccharides that are more commonly expected to transit the gastrointestinal tract, and little is known about its direct interaction with the gut microbiota, which plays a central role in digestion of other dietary fiber polysaccharides. Here, we show that the ability to digest xanthan gum is surprisingly common in industrialized human gut microbiomes and appears contingent on a single uncultured bacterium in the family
Ruminococcaceae
. Our data reveal that this primary degrader cleaves the xanthan gum backbone before processing the released oligosaccharides using additional enzymes. Surprisingly, some individuals harbor a
Bacteroides intestinalis
that is incapable of consuming polymeric xanthan gum but grows on oligosaccharide products generated by the
Ruminococcaceae
. Feeding xanthan gum to germfree mice colonized with a human microbiota containing the uncultured
Ruminococcaceae
supports the idea that this additive can drive expansion of this primary degrader along with exogenously introduced
Bacteroides intestinalis
. Our work demonstrates the existence of a potential xanthan gum food chain involving at least two members of different phyla of gut bacteria and provides an initial framework to understand how widespread consumption of a recently introduced food additive influences human microbiomes.