Modulation of the intestinal microbiota and immune system of farmed sparus aurata by the administration of the yeast Debaryomyces hansenii L2 in conjunction with inulin

Abstract

Fish gastrointestinal tract is one of the most important sites of interaction with the external world. Interactions between the intestinal microbiota and the host modulate the functionality of the intestinal mucosa and gene expression. Application of probiotics, prebiotics and synbiotics for aquatic animals is increasing to improve welfare and promote growth. However, data about the use of probiotics in conjunction with prebiotics, in farmed marine organisms are scarce. The objective of this work is to study the modulation ability of the intestinal microbiota and the immune system of gilthead seabream exerted by the probiotic yeast Debaromycess hansonii L2 in conjunction with the prebiotic inulin. Fish were fed a commercial diet (control diet I), and with the same diet supplemented with 1.1% D. hansenii strain L2 (106 CFU g-1) plus inulin (3%) (diet II) for 4 weeks. The whole intestines of healthy fish from each group were aseptically removed at 2 and 4 weeks after starting the experiment and they were analysed by PCR-Denaturing Gradient Gel Electrophoresis (DGGE). Samples of blood and head kidney were obtained for humoral and cellular immune parameters determination. The expression of 12 selected genes related to the immune response (IgM, MHCIα, MHCIIα, C3, IL-1β,TLR, TNFα, CSF-1R, NCCRP-1, Hep, TCRβ y CD8) were analyzed by real-time PCR from skin, intestine, liver and head-kidney tissue. In this study, relevant changes in the intestinal microbiota of gilthead seabream specimens fed the diets assayed has been demonstrated. An important effect on the intestinal microbiota by the dietary administration of a synbiotic mixture has also been detected, especially in fish receiving the supplemented diet for 4 weeks. These changes coincided in the same time with an up-regulation of the expression of immunological genes in skin and head kidney of gilthead seabream at 2 and 4 weeks, respectively. © 2011 Tapia-Paniagua ST, et al.