Prevotella copri

Since the advent of human microbiome studies almost 20 years ago, the gut and oral microbe Prevotella copri has been repeatedly discovered and mentioned in microbiome profiling studies. Due to the wide distribution and variable abundance of this intriguing microbe, there are conflicting reports on whether it is beneficial or harmful to human health, the extent to which it affects various conditions, and whether these effects are causal or merely associated.

Prevotella copri is a common member of the human gastrointestinal microbiome whose relative abundance has been associated with positive and negative effects on diseases such as Parkinson's and rheumatoid arthritis. However, the definitive role of P. copri in human health and the effects of different diets on its relative abundance in the gut microbiome are not yet clear.

Since the first studies on the human microbiome, it has been observed that the two genera Prevotella and Bacteroides are inversely correlated, i.e. a high abundance of P. copri was often associated with a low abundance of Bacteroides. This observation led to a widely hypothesized existence of different microbiome "enterotypes", (Arumugam M et al. (2011) and was attributed to the fact that both genera belong to the same class and strive for the same nutrients (Wu GD et al. 2011)

Nutrition, metabolism and adaptation to the human gut: P. copri can feed on a range of nutrients, including complex polysaccharides. The polysaccharide utilization loci (PULs) proposed by Bjursell et al. (Bjursell MK et al.2006) are a set of genes encoding proteins required for the metabolism and transport of complex polysaccharides in prokaryotes. Their products enable the human gut microbiota to adapt to changes in host development and nutrition (Bjursell MK et al.2006). In P. copri, such loci are widespread and both distinct and characteristic. I.e.: P. copri has unique PULs that vary between different strains, and their gene products can break down a wide range of plant (but not animal) polysaccharides in the human gut (Fehlner-Peach H et al. 2019).

Various studies suggest that Prevotella thrives on plant or fiber-rich foods. These include diets commonly described as non-Western, Mediterranean or rural African diets. The utilization of plant polysaccharides was compared with that of P. copri growing in culture media alone or together with Candida spp. Starch and carboxymethylcellulose did not promote the growth of P. copri (Pareek S et al. 2019). Wheat bran extract enriched with arabinoxylan oligosaccharides promoted the growth of Prevotella species, especially P. copri (Pareek S et al. 2019). While in one study the fermentation of wheat bran was suggested to be the cause of the enrichment of the fecal microbiota with P. copri, a diet containing wheat peptides and the fucose-rich sulfated polysaccharide fucoidan reduced the relative abundance of P. copri and was suggested to alleviate chronic gastritis (Kan J et al. (2020). Although dietary fiber may have an impact on Prevotella, it remains difficult to find a specific dietary fiber that can enrich this versatile organism.

The Western diet is high in fat, sugar and fiber. It is characterized by a high proportion of processed foods. Limiting the advanced glycation end products found in the Western diet led to a significant reduction in the incidence of P. copri (Yacoub R et al. (2017). Interestingly, however, one study demonstrated that a high relative incidence of P. copri was associated with a high-protein and Western diet. The metabolic machinery of P. copri could be a great evidence of genomic and functional variability at the strain level, allowing P. copri to easily adapt to the type of nutrients available in the gut: while some strains are able to degrade carbohydrates and fibers, others are able to biosynthesize branched-chain amino acids (BCAAs) from meat-based diets.

Another finding related to the metabolizing power of P. copri is its ability to detoxify superoxide radicals and tolerate reactive oxygen species that could otherwise increase inflammation (Schwimmer JB et al. 2019). The inconsistent response of Prevotella to diet may be due to the interplay between host genetics and microbe-microbe interactions. Environmental factors and host habits may also contribute to another dimension of variation: geographic variation.

Prevotella copri is one of the main species of the genus Prevotella and is frequently found in the human body, particularly in the oral cavity and gastrointestinal tract. It is an anaerobic, gram-negative, non-spore-forming bacterium. The name Prevotella (derived from the name of the French microbiologist A. R. Prévot) was officially assigned to the genus in 1990 to distinguish "moderately saccharolytic, predominantly oral Bacteroides species" from other Bacteroides, while the species P. copri (from the ancient Greek copron = faeces or faecal matter) was only recognized taxonomically in 2007 and belongs to the faecal Prevotella strains.

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