Aquaculture Europe 2023

September 18 - 21, 2023


Add To Calendar 21/09/2023 15:45:0021/09/2023 16:00:00Europe/ViennaAquaculture Europe 2023YEAST CELL WALL DERIVED FROM Saccharomyces cerevisiae DIFFERENTIALLY SHAPE INTESTINAL INNATE IMMUNITY AND MUCOSAL TISSUE RESPONSES OF ZEBRAFISH Danio rerioSchubert 1The European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982


 M. Rawlinga*,  M. Schiavoneb ,  D.  L. Merrifielda ,  E. Apperb , M. Castexb,  E. Leclercqb*,  A. Foeya


aUniversity of Plymouth, Drake Circus, PL48AA, UK.

b Lallemand SAS, 19 rue des B riquetiers, 31700, Blagnac, France




 YCWs are proven immune response modifiers holding an important position among multifarious paraprobiotics and, in fish, have been implicated in the maintenance of (intestinal ) mucosal health and integrity, disease resilience and animal performance. T he major structural components of YCWs are  β-glucans and mannanoligosaccharides (MOS)  which  act as  microbe-associated molecular patterns (MAMPs)  that can be  recognized  by the  pattern recognition receptors of the host immune system.  YCW can vary in their biochemical composition and molecular structure due to the yeast species, strain, fermentation, and down-processing conditions . Such diversity  of MAMPs structure and profile  could elicit distinct host immune responses and to date has been under evaluated.  The current investigation aimed to characterise the biochemical and molecular properties of four proprietary S.  cerevisiae  YCW fractions of discrete origin. Our hypothesis was that the biophysical characteristics of given S.  cerevisiae  will elicit distinct immune responses, which has not been previously addressed using a purposely designed comparative study. 

Materials and Methods

A  5-week trial (Plymouth, UK)  tested 5  dietary  groups in triplicate using  wild-type adult zebrafish (BWi  = 0.80 ± 0.02 g; 25 fish/tank)  and a  basal diet  formulated to  NRC requirements for cyprinids (36% protein, 8% lipid). Treatments  consisted of 1]  non-supplemented  basal diet (Control), and basal diet supplemented with 2] YCW1, 3]  YCW2, 4] YCW3, 5] YCW4 . A ll YCW fractions  were supplemented at 2.0 kg/T of feed and  consisted of  contrasted  proprietary YCW strains  provided by  Lallemand  SAS  (France).  YCW fractions were assessed by sulfuric acid method. D iets were fed  at  fixed rate of 4 % biomass daily  over 3 daily rations .  At the end of the trial,  intestinal  and skin histomorphometry (n = 9 fish/ treatment)  as well as the  intestinal gene expression analysis (n = 6 fish/ treatment) was assessed . For gene expression analysis d ifferences between control and experimental groups were assessed by non-parametric permutation test with  significance accepted at p < 0.05. All other data was analysed by O ne-way ANOVA and significance accepted at p < 0.05.


The biochemical analysis revealed significant differences in percentage composition of β-glucan and  alpha - mannan polysaccharides in each YCW fraction (Fig 1 ;  < 0.05).  Histological appraisal revealed significantly elevated GCD, IELs and acidomucins in YCW1, 2 and 3 groups containing higher levels of mannan content compared to YCW4 (Fig 2;  < 0.05). Gene expression analysis revealed differential modulation in markers for innate immune pattern recognition receptors (PRRs) and signal transduction factors, transcription and innate cytokines that suggest polarisation of responses to Th1, Th17, Tr1 and Foxp3+-Tregs according to each YCW group (Fig 3 ). 


 This study identifies marked intra-species variability in the molecular properties of S. cerevisiae yeast cell wall fraction. T he α-mannan content  was associated with  GCD and IEL hyperplasia suggestive of fortifying intestinal barrier integrity and immune competence. The gene expression analysis revealed  marked  modification in  the  expression pattern of  PRRs  when fed  contrasted  YCW fractions . Furthermore, the gene expression patterns for transcription factors and cytokine responses suggest the preferential mobilisation of distinct T-helper cell subsets for Th1, Th17, TR1 and Foxp3+ -Tregs, indicating a particular potential for each YCW fraction to confer protection against infectious agents and, or non-infectious pathologies .  Accordingly, this study highlights the  potential of considering the biophysical characteristics of the YCW to apprehend their specific immune properties and elicit targeted immune functionalities towards precision functional nutrition in Aquaculture.