The effect of dietary chitin on Atlantic salmon (Salmo salar) chitinase activity, gene expression, and microbial composition

ABSTRACT Background Chitin is a common component in the natural diet of many fish, and a range of chitinases with the potential to down chitin have been identified. Yet whether chitin is metabolized in fish is still unclear. Here we used a combination of chitinase activity assay, transcriptomics, and 16S rRNA bacterial analysis to assess the effect of chitin supplementation on Atlantic salmon gene expression and microbial community. Results Atlantic salmon express multiple genes associated with chitin metabolism, and we show that the expression and activity of Atlantic salmon chitinases are not affected by the addition of dietary chitin. We do, however, demonstrate an association between gut microbial composition, chitinase activity in the gut, and host chitinase expression. Conclusion The findings presented here support the idea that chitin metabolism genes are linked to the maintenance of a chitin-based barrier in the teleost gut. These results contribute to a greater understanding of chitin metabolism in fish.