Intestinal microbiota variation in Senegalese sole (Solea senegalensis) under different feeding regimes

The aim of this study was to determine the influence of the feeding regimes in Senegalese sole (Solea senegalensis) cultured under extensive, semi‐extensive and intensive production systems. A total of 254 bacterial isolates from guts of fish cultured under different production systems and feeding regimes were tested. Biochemical tests and genetic analyses based on the 16S rDNA sequence analysis were conduced to identify bacterial strains. Vibrio species were the most represented taxonomic group in the culturable microbiota of S. senegalensis guts tested. Particularly, Vibrio ichthyoenteri was the most frequently isolated Vibrio species. Comparison among diets showed a significant reduction (P<0.05) in vibrio percentages and a higher occurrence of Shewanella species in Senegalese soles fed polychaeta. In addition, a major influence of environmental temperature on microbiota composition was detected. Cold temperatures brought about a change in the percentages of Vibrio species and a higher representation of α‐Proteobacteria in both outdoor systems (extensive and semi‐extensive). The significant differences between intestinal bacterial composition in Senegalese soles fed commercial diets and natural preys (polychaeta) reveal the necessity to develop specific optimized diets for the intensive rearing of this fish species.