Purushothaman, Kathiresan, Rocha, Sérgio D.C., Kaul, Daanish, Goksu, Aleksandar B., Morales-Lange, Byron, Crawford, Alexander D., Mydland, Liv Torunn, Sørum, Henning, Qingsong, Lin, Vij, Shubha, Øverland, Margareth, and Press, Charles Mc L. (2025) Dietary yeast improves zebrafish immunity and survival against Aeromonas infection. Fish and Shellfish Immunology, 167. 110678.

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Abstract

This study aimed to evaluate the potential of autolysed Cyberlindnera jadinii yeast (ACJ) as a functional feed additive to enhance intestinal immunity and disease resistance in zebrafish (Danio rerio) following a bacterial challenge with Aeromonas salmonicida subspecies salmonicida. Zebrafish were fed either a control or a ACJ-supplemented diet for 2 weeks, followed by bath exposure to A. salmonicida subspecies salmonicida. To achieve this, post-challenge responses were assessed using a multi-method approach, including mortality tracking, bacterial detection by qPCR, histology, immunohistochemistry, and proteomic analyses (iTRAQ and SWATH-MS). Fish fed the ACJ diet exhibited significantly lower mortality (0.8 %) compared to the control group (7.5 %) (P = 0.0104, log-rank test). PCR analysis confirmed a reduced bacterial load in the ACJ group over time. Immunohistochemistry showed enhanced recruitment of macrophages and neutrophils in the ACJ-fed fish, particularly at Day 1 and Day 5 post-infection. Proteomic profiling of intestinal tissue identified 792 differentially abundant proteins (≥1.3-fold or ≤0.77-fold; P < 0.05), including those involved in phagosome formation, necroptosis, tight junction regulation, and arginine-proline metabolism. These findings demonstrate that dietary ACJ significantly enhances the innate immune response and confers increased resistance to A. salmonicida infection in zebrafish, supporting its potential as a functional feed ingredient in aquaculture.

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