Dietary Probiotic Bacillus licheniformis TC22 Increases Growth, Immunity, and Disease Resistance, against Vibrio splendidus Infection in Juvenile Sea Cucumbers Apostichopus japonicus

Abstract

In this study we examined the effects of probiotic Bacillus licheniformis TC22 on growth, immunity, and disease resistance against Vibrio splendidus in juvenile sea cucumbers Apostichopus japonicus. For 30 days, sea cucumbers were fed diets with TC22 at 0 (control), 105, 107, and 109 CFU/g respectively. Results showed that dietary TC22 at 109 CFU/g significantly improved (P<0.05) growth of sea cucumbers. Dietary TC22 had no significant effects on total coelomocytes count, acid phosphatase activity, and superoxide dismutase activity in these animals (P>0.05). Dietary TC22 at 109 CFU/g significantly improved phagocytosis, and total nitric oxide synthase activity in sea cucumbers (P<0.05). Compared to the control, dietary TC22 had no significant effects on respiratory burst activity (P>0.05). Respiratory burst in sea cucumbers fed dietary TC22 at 109 CFU/g was significantly higher than those fed dietary TC22 at 107 CFU/g (P<0.05). Cumulative mortality after V. splendidus challenge decreased significantly in the sea cucumbers fed with TC22 at 109 CFU/g (P<0.05). The present study confirmed dietary B. licheniformis TC22 at 109 CFU/g could significantly improve immunity and disease resistance in juvenile A. japonicus.