Differential response of digesta- and mucosa-associated intestinal microbiota to dietary insect meal during the seawater phase of Atlantic salmon

Abstract Background Intestinal digesta is commonly used for studying responses of microbiota to dietary shifts, yet evidence accumulating that it represents an incomplete view the intestinal microbiota. The present work aims investigate differences between digesta- and mucosa-associated in Atlantic salmon ( Salmo salar ) how they may respond differently perturbations. In a 16-week seawater feeding trial, were fed either commercially-relevant reference diet or insect meal containing ~ 15% black soldier fly Hermetia illucens larvae meal. distal profiled by 16S rRNA gene sequencing. Results Regardless diet, we observed substantial Microbial richness diversity much higher than mucosa. altered resulting microbial diversity. effect, however, depended on sample origin. Digesta-associated showed more pronounced changes Multivariate association analyses identified two mucosa-enriched taxa, Brevinema andersonii Spirochaetaceae , associated with expression genes related immune barrier function intestine, respectively. Conclusions Our data show mucosa harbor communities clear differences. While insects increased both microbiota, seems resilient variations composition. To fully unveil response changes, concurrent profiling recommended whenever feasible. Specific taxa enriched are function. Detailed studies needed ecological functional significance dwelling