A Tentative Study of the Effects of Heat-Inactivation of the Probiotic Strain Ppd11 on Senegalese Sole () Intestinal Microbiota and Immune Response.

Concerns about safety, applicability and functionality associated with live probiotic cells have led to consideration of the use of non-viable microorganisms, known as paraprobiotics. The present study evaluated the effects of dietary administration of heat-inactivated cells of the probiotic strain Ppd11 on the intestinal microbiota and immune gene transcription in . Results obtained were evaluated and compared to those described after feeding with viable Pdp11 cells. specimens were fed with basal (control) diet or supplemented with live or heat inactivated (60 °C, 1 h) probiotics diets for 45 days. Growth improvement was observed in the group receiving live probiotics compared to the control group, but not after feeding with a probiotic heat-inactivated diet. Regarding immune gene transcription, no changes were observed for , , , , , and in the intestinal samples based on the diet. On the contrary, , , , , , and transcription were modulated after probiotic supplementation, though no differences between viable and heat-inactivated probiotic supplemented diets were observed. Modulation of intestinal microbiota showed remarkable differences based on the viability of the probiotics. Thus, higher diversity in fish fed with live probiotic cells, jointly with increased and to the detriment of , was detected. However, microbiota of fish receiving heat-inactivated probiotic cells showed decreased and increased and genus abundance. In short, the results obtained indicate that the viable state of Pdp11 probiotic cells affects growth performance and modulation of intestinal microbiota. On the contrary, minor changes were detected in the intestinal immune response, being similar for fish receiving both, viable and inactivated probiotic cell supplemented diets, when compared to the control diet.