Evaluation of paraprobiotic applicability of Clostridium butyricum CBG01 in improving the growth performance, immune responses and disease resistance in Pacific white shrimp, Penaeus vannamei

The present study evaluated the growth performance, non-specific immunity and disease resistance in Penaeus vannamei fed diets supplemented with live or dead cells of Clostridium butyricum CBG01 (live cells, CB; sonication-killed cell-free extracts, UI; heat-killed whole-cell, HI; fermentation supernatant, FS; the control, the basal diet without C. butyricum, DZ) for 42 days. Results indicated that the final weight, specific growth rate, survival rate and feed efficiency rate of shrimp in the treatment groups were significantly improved versus the control (P < 0.05). The challenge test of Vibrio parahaemolyticus showed that the cumulative mortalities of shrimp in the CB and UI groups were significantly lower than that in the control (P < 0.05). Compared with the control, alkaline phosphatase, acid phosphatase, total nitric oxide synthase, lysozyme, peroxidase, superoxide dismutase activities, total antioxidant capacity, and phenonoloxidase content in the serum and the relative expression levels of SOD, LZM, proPO, LGBP, HSP70, Imd, Toll, Relish, TOR, 4E-BP, eIF4E1α, eIF4E2 genes in the hepatopancreas of CB and HI shrimp groups were all significantly enhanced, and those were significantly improved in the UI group as well, except for phenonoloxidase content, relative expression levels of SOD, Imd and eIF4E2 genes (P < 0.05). However, immune responses were induced partially in the FS shrimp group. These results suggested that dietary both live and dead cells of C. butyricum CBG01 could improve the growth performance and immune responses of shrimp. When resistance against Vibrio parahaemolyticus in shrimp is considered, sonication-killed cell-free extracts of C. butyricum showed a better effect than heat-killed whole-cells of probiotic. Considering collectively the above, sonication-killed cell-free extracts of C. butyricum could be applied as a potential paraprobiotic to enhance the growth performance, immunity capacity and disease resistance of P. vannamei.