Aquaculture Europe 2023

September 18 - 21, 2023


Add To Calendar 21/09/2023 16:00:0021/09/2023 16:15:00Europe/ViennaAquaculture Europe 2023CAN THE GENETIC BACKGROUND OF GILTHEAD SEA BREAM CHANGE THE ACTION OF FEED ADDITIVES?  ANSWERS FROM GUT MICROBIOME AND TRANSCRIPTOME INTERACTIONSSchubert 5The European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982


F. Naya-Català1*, M.C. Piazzon1 ,  S. Torrecillas2 ,  J. Calduch-Giner1 ,  R. Fontanillas3 ,  B. Hostins4, A. Sitjà-Bobadilla1 ,  D. Montero2 ,  J. Pérez-Sánchez1.


1 Nutrigenomics and  Fish P athology Groups of Institute of Aquaculture Torre de la Sal (IATS, CSIC), Spain. 2 Grupo de Investigación en Acuicultura (GIA), IU-ECOAQUA,  Universidad de las Palmas de Gran Canaria, Spain ,3 Skretting Aquaculture Research Centre, Norway, 4 INVE Technologies NV, Belgium.  E-mail:


The sustainable growth of modern aquaculture must rely in the production of healthy and robust fish fed with diets overcoming the dependence on fish meal (FM) and fish oil (FO). S elective breeding  and  functional feed s should be keystones towards this development ,  though  most of their synergies remains mostly unexplored. Certainly, recent studies i n gilthead sea bream highlighted that s election  for growth co-selects for a  plastic  microbiota capable of exerting a wide nutritionally-mediated  metabolic response with less community changes (Piazzon et al., 2020) . Otherwise, t he use of feed additives  as boosters of  overall  fish performance has  expanded rapidly as an alternative  to antibiotics and chemotherapeutics, with also the capacity to modify the gut microbiota  and host  transcriptional associations . However, we are far from establishing the ultimate mode of action of each feed additive for a given genetic background.  To bridge this gap, we investigated the  effect of a battery of feed additives  upon gut microbiota and host transcriptomics  in reference (REF) gilthead sea bream  and genetically  improved fish  for growth (GS) within the PROGENSA® selection program.

 Material and methods

 Estimated breeding values ranged between -159.14 for REF fish and +223.18 for GS fish.  The basal diet (CTRL; no feed additive) was formulated by Skretting to be a low FM diet ( 7.5%),  completely devoid of FO. Feed additives (INVE Technologies) added to CTRL diet by oil-coating included  a phytobiotic based on natural plant extracts (PHY), a mixture of organic acids (OA), and a Bacillus-based probiotic (PROB). After an acclimation period of two weeks with the CTRL diet, fish continued to be fed with either CTRL, PHY, OA or PROB diets until the end of  the  trial (97 days). At this end-point,  tissue portions of anterior  intestine  (AI) were taken  for transcriptional (RNA-seq) and AI scrapped mucus for adherent microbiota analyses, using the Illumina platform and RDP database. Additionally, AI and posterior intestine (PI) sections  were  used for histological survey.


 The GS fish presented higher growth rates and condition factors, lower feed conversion ratios, and an enhanced homogeneity in terms of microbiota composition, regardless  of the additive. The PHY effects were especially remarkable in the intestinal transcriptome of higher growth GS-PHY fish, with a particular up-regulation of markers of epithelial integrity (vil1 , chmp2a-b , vps4b), sphingolipid metabolism (degs1 , elovl1 , sgpp1 , plekha8 ),  high-density lipoproteins secretion to vascular tissues (abcg8 , abca1 , nr1h3), and bile salt-activated lipase and receptor (cel , nr1h4 ). Facing OA, the gut adherent microbiota of REF fish shifted towards a less pathogenic profile, with a reduction in Staphylococcus , Streptococcus , and Neisseria genera correlated with neutrophil degranulation genes . This profile  showed inferred  bacterial  processes involving organic acid s, such as ABE fermentation and TCA cycle, and was prone to exert vitamin K bi osynthesis. The Bacillus-based PROB diet affected both microbiome and transcriptome features . Bacillus  genus was stablished  in the fish gut  regardless  of the fish genotype ,  and  anti-inflammatory histology patterns were increased in the AI and PI of PROB fish.  GS-PROB  showed an  increased proportion of  the  nitrate reducer Kocuria ,  and a reduction of  the pathogenic Photobacterium damselae , in parallel with a better feed efficiency of GS-PROB fish  than  the rest of  the groups .  This group  also  showed  the up-regulat ion of markers of epithelial regeneration and integrity (ezr , ncstn , plec , and neurog3) in concurrence with the down-regulation of markers of protein synthesis, that  correlated with Chromohalobacter , Enhydrobacter , Vibrio , and Acinetobacter.

Concluding remarks

 As a general rule, it was confirmed that the gut microbiota variability among individuals was drastically reduced in GS fish (Naya-Català et al., 2022) . T he intensity and the specific effect of a given additive upon host transcriptomics and  gut microbiota  varied depending  on  the genetic background (Figure 1) . Thus, PHY only shaped the transcriptome of GS fish. Conversely, OA shaped the gut microbiota of REF fish, whereas PROB triggered changes in both host transcriptome and gut microbiota of  both GS and REF fish. Altogether, this work has generated a list of taxa and transcripts associated to a particular feed additive and fish genotype, which might help nutritionists, breeders and farmers to know which microbial and host elements are susceptible to be targeted in order to preserve and improve  the gut function  of  PROGENSA® farmed fish.


Naya-Català F. et  al.  (2022); Biology, 11:1744.

 Piazzon M.C. et al. (2020); Microbiome, 8:168.

Funding : AquaIMPACT (H2020 #818367); Bream-AquaINTECH (RTI2018–094128-B-I00) ; RYC2018-024049-I/AEI/10.13039/501100011033.