Gut bacteria associated with different diets in reared Nephrops norvegicus

The impact of different diets on the gut microbiota of reared Nephrops norvegicus was investigated based on bacterial 16S rRNA gene diversity. Specimens were collected from Pagasitikos Gulf (Greece) and kept in experimental rearing tanks, under in situ conditions, for 6 months. Treatments included three diets: frozen natural (mussel) food (M), dry formulated pellet (P) and starvation (S). Gut samples were collected at the initiation of the experiment, and after 3 and 6 months. Tank water and diet samples were also analyzed for bacterial 16S rRNA gene diversity. Statistical analysis separated the two groups fed or starved (M and P vs. S samples). Most gut bacteria were not related to the water or diet bacteria, while bacterial diversity was higher in the starvation samples. M and P samples were dominated by Gammaproteobacteria, Epsilonproteobacteria and Tenericutes. Phylotypes clustering in Photobacterium leiognathi, Shewanella sp. and Entomoplasmatales had high frequencies in the M and P samples but low sequence frequencies in S samples. The study showed that feeding resulted in the selection of specific species, which also occurs in the natural population, and might be associated with the animal's nutrition.