TY - JOUR T1 - Differential Response of Digesta- and Mucosa-Associated Intestinal Microbiota to Dietary Black Soldier Fly (<em>Hermetia illucens</em>) Larvae Meal in Seawater Phase Atlantic Salmon (<em>Salmo salar</em>) JF - bioRxiv DO - 10.1101/2020.05.08.083899 SP - 2020.05.08.083899 AU - Yanxian Li AU - Leonardo Bruni AU - Alexander Jaramillo-Torres AU - Karina Gajardo AU - Trond M. Kortner AU - Åshild Krogdahl Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/05/09/2020.05.08.083899.abstract N2 - Intestinal digesta is commonly used for studying responses of microbiota to dietary shifts, yet evidence is accumulating that it represents an incomplete view of the intestinal microbiota. In a 16-week seawater feeding trial, Atlantic salmon (Salmo salar) were fed either a commercially-relevant reference diet or an insect meal diet containing ∼15% black soldier fly larvae meal. The digesta- and mucosa-associated distal intestinal microbiota were profiled by 16S rRNA gene sequencing. Regardless of diet, we observed substantial differences between digesta- and mucosa-associated intestinal microbiota. Microbial richness and diversity were much higher in the digesta than the mucosa. The insect meal diet altered the distal intestinal microbiota resulting in higher microbial richness and diversity. The diet effect, however, depended on the sample origin. Digesta-associated intestinal microbiota showed more pronounced changes than the mucosa-associated microbiota. Lastly, multivariate association analyses identified two mucosa-enriched taxa, Brevinema andersonii and unclassified Spirochaetaceae, associated with the expression of genes related to immune responses and barrier function in the distal intestine, respectively. Overall, our data clearly indicate that responses in digesta- and mucosa-associated microbiota to dietary inclusion of insect meal differ, with the latter being more resilient to dietary changes.IMPORTANCE While fecal samples provide a convenient, non-invasive way for profiling intestinal microbiota, heterogeneity in the microbial community assemblage between intestinal digesta and mucosa is well recognized. The present work provides insights into the differences between digesta- and mucosa-associated intestinal microbiota in Atlantic salmon and how they respond differently to dietary perturbations. Mucosa-associated intestinal microbiota seemed more resilient to variation in diet composition than digesta-associated intestinal microbiota. Most likely, not only the digesta associated microbiota, but also the mucosa-associated, play key roles in shaping the host metabolism. Therefore, our work emphasizes the necessity of profiling both digesta- and mucosa-associated intestinal microbiota to understand the impact of variation in diet composition on intestinal microbiota.Competing Interest StatementThe authors have declared no competing interest. ER -