The response of gut and fecal bacterial communities of the European sea bass (Dicentrachus labrax) fed a low fish-plant meal and yeast protein supplementation diet

Abstract

Abstract As aquaculture is nowadays the major fish-food production sector, continuous research is undergoing for aquafeeds that could replace conventional fishmeal in order to enhance its environmental and economic sustainability. Fish gut microorganisms might be involved in nutrient assimilation and thus they are crucial for their hosts’ well-being. In this study, the bacterial diversity was investigated by16S rRNA gene metabarcoding in order to investigate changes in midgut (M) and feces (F) microbiota of sea bass Dicentrachus labrax fed with conventional (C) and innovative-low fish meal diet (I), aiming at discovering microbiota that could be associated with the enhancement of host's health and productivity. Our results indicated that Proteobacteria (Pseudomonadota) prevailed in all samples followed by Firmicutes (Bacillota) or Bacteroidota (mostly in feces), while fecal communities were richer. Taxonomic distributions at the operational taxonomic unit level in midgut samples revealed differentially abundant fermentative species that prevailed in individuals fed with the innovative diet. Especially Staphylococcus was more abundant in MI samples implying enhancement from ingredients present only in the innovative diet and implying that this feed shapes rather favorable microbiota, which could support the digestion and good growth performance in aquaculture.