Yarrowia lipolytica yeast as a dietary supplement for rainbow trout (Oncorhynchus mykiss): Effects on gut microbiota, health and immunity

This study evaluated the effect of whole and autolysed Yarrowia lipolytica CBS 7504 strain on growth performance, gut immunity and gut microbiota composition in juvenile rainbow trout (Oncorhynchus mykiss). Fish were fed diets containing 2% and 5% whole or autolysed Y. lipolytica (WY and AY) in a 45-day trial, with a no-yeast diet as control. Log2 fold change analysis of Y. lipolytica diets showed relative change in abundance and association of certain microbial taxa with respect to control such as a correlation between the relative abundance of Desulfovibrionaceae in diets with WY. Moreover, diets at 5% and 2% levels demonstrated a synergistic association with relative levels of Sphingobacteriaceae and Rhodobacteraceae, respectively. However, the overall analyses showed little/no impact of Y. lipolytica supplementation on overall intestinal microbial composition, growth parameters and body indices. Gene expression analysis of the intestine revealed significant elevation in expression of immune-related genes of the complement pathway (c3 and c-type lectin), membrane receptor pathway (tlr2 and tlr5), mucosal innate immune pathway (muc-2), cytokines (tnf-alpha) and adaptive immune pathway (igt and cd4) in 5% WY. In conclusion, it can be inferred that dietary Y. lipolytica can be a useful functional feed supplement for rainbow trout when used as whole yeast at a 5% inclusion level since it can modulate gut microbial communities and act as a potential immunostimulant for the host.