Differential response of digesta- and mucosa-associated intestinal microbiota to dietary black soldier fly (Hermetia illucens) larvae meal in seawater phase Atlantic salmon (Salmo salar)

Abstract

Background: 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. The present work aims to investigate the differences between digesta- and mucosa-associated intestinal microbiota in Atlantic salmon ( Salmo salar ) and how they may respond differently to dietary perturbations. In a 16-week seawater feeding trial, Atlantic salmon were fed either a commercially-relevant reference diet or an insect meal diet containing ~15% black soldier fly ( Hermetia illucens ) larvae meal. The digesta- and mucosa-associated distal intestinal microbiota were profiled by 16S rRNA gene sequencing. Results: 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. 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. Conclusions: Our data show that salmon intestinal digesta and mucosa harbor microbial communities with clear differences. Mucosa-associated intestinal microbiota seems more resilient to variations in the diet composition than digesta-associated intestinal microbiota. To fully unveil the response of intestinal microbiota to dietary changes, concurrent profiling of digesta- and mucosa-associated intestinal microbiota is recommended whenever feasible.

Response of gut microbiota to feed‐borne bacteria depends on fish growth rate: a snapshot survey of farmed juvenile Takifugu obscurus

“…Among others, Pseudomonas is the most frequently reported gut‐associated bacteria across many different freshwater fish species (Egerton, et al ., 2018). On the other hand, recent studies had also raised concerns that it might represent a common contaminating bacterial taxa in molecular biology reagents (Li, et al ., 2020a). While considering the very rare presence of Pseudomonas in all the water and sediment samples (Fig.…”

Intestinal microbial communities of rainbow trout (Oncorhynchus mykiss) may be improved by feeding a Hermetia illucens meal/low-fishmeal diet

“…However, few information is available about IM modulatory effect on fish intestinal microbiota (Parma et al 2016;Bruni et al 2018;Huyben et al 2019;Belghit et al 2019;Rimoldi et al 2019;Terova et al 2019;Józefiak et al 2019a, b;Osimani et al 2019;Li et al 2020a). Indeed, only few studies have investigated the effect of dietary Hi meal inclusion on the gut bacterial communities of rainbow trout using highthroughput sequencing technologies (Huyben et al 2019;Rimoldi et al 2019;Terova et al 2019).…”