Probiotic effects of the Bacillus velezensis GY65 strain in the mandarin fish, Siniperca chuatsi

Abstract Traditional culture of the mandarin fish (Siniperca chuatsi), an important freshwater fish in China, is restricted by live bait fish, as the difficulty of utilizing plant-derived nutrients in its artificial feed hinders its industrialization of artificial feed. This study evaluated the effect of the Bacillus velezensis GY65 strain, which shows probiotic effects on digestive and bacterial infections in mandarin fish. The complete genome of B. velezensis GY65 was obtained via sequencing. Seven amylase coding genes that could improve the fish digestion of plant feeds were identified. Twelve gene clusters of secondary metabolites related to antibacterial compounds were identified using the antiSMAH database. The effects of B. velezensis GY65 on growth performance, digestive enzyme capacity, antioxidant capacity, and innate immune response of mandarin fish were evaluated. The results showed a significantly (P