The effects of amino acids and fatty acids on the disease resistance of Epinephelus fuscoguttatus in response to Vibrio vulnificus infection

Mass mortality resulting from bacterial infection poses a major problem in the grouper aquaculture industry. The purpose of this study was to profile the metabolites released in challenged fish and to reconstruct the metabolic pathways of brown marble grouper (Epinephelus fuscoguttatus) in response to Vibrio vulnificus infection. Metabolite profiles from control and challenged treatment groups after feeding were determined using gas chromatography-mass spectrometry (GC-MS). Forty metabolites were identified from the GC-MS analysis. These metabolites comprised of amino acids, fatty acids, organic acids and carbohydrates. The profiles showed the highest percent area (33.1%) for leucine from the amino acid class in infected fish compared to the control treatment group (12.3%). Regarding the fatty acid class, a higher percent area of the metabolite 8,11-eicosadienoic acid (27.04%) was observed in fish infected with V. vulnificus than in the control treatment group (22.5%). Meanwhile, in the carbohydrate class, glucose (47.0%) was the metabolite in the carbohydrate class present at highest percentage in the control treatment group compared to infected fish (30.0%). Our findings highlight the importance of a metabolic analysis for understanding the changes of metabolites in E. fuscoguttatus in response to bacterial infections.