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.