Effects of a novel marine probiotic, Lactobacillus plantarum AH 78, on growth performance and immune response of Nile tilapia ( Oreochromis niloticus )

Aims Evaluation of the efficacy of marine lactic acid bacteria, Lactobacillus plantarum AH 78, on growth performance and immune response of Nile tilapia ( Oreochromis niloticus ) challenged with Aeromonas hydrophila . Methods and Results Marine probiotic, Lact. plantarum AH 78, was incorporated in Nile tilapia diets at 0·0, 0·5, 1·0 or 2·0% (w/w). The diets were fed to juvenile Nile tilapia for 40 days, after which they were challenged with pathogenic bacterium, Aer. hydrophila . The best growth rates and feed efficiency were obtained at 0·5% probiotic, while fish survival was not affected by dietary probiotic. After challenge with Aer. hydrophila immunological responses and survival were recorded at 1·0% probiont. Likewise, significant up‐regulation of the expression of cytokine genes, IL‐4, IL‐12 and IFN‐γ, in fish livers was found at 1·0% probiont, compared to the control diet. Concomitantly, AH 78 colonized the intestinal mucosa of treated fish, even after reverting to the control diet, and remained viable in the feed stored at 4°C up to 12 months. Conclusions Marine Lact. plantarum AH 78 at 0·5–1·0% inclusion level conferred the best performance and immune response of Nile tilapia challenged with Aer. hydrophila . Significance and Impact of the Study Marine Lact. plantarum AH 78 could be considered as a potential probiotic to control disease outbreaks in farmed Nile tilapia.