A Comparative Study on Effects of Three Bacillus Species on the Growth Performance, Non-Specific Immunity and Disease Resistance of Penaeus vannamei

An experiment was conducted to study the effect of adding three Bacillus species to feed on the growth performance, non-specific immunity and disease resistance of Penaeus vannamei. Shrimp was fed with the basal diet supplemented with Bacillus subtilis BSXE-1601 (BD group), B.cereus BCXE-01 (CD group) and B.velezensis 26.3 (BV group) at a density of 1×10⁹ CFU·kg^-1 in the basal diet. The basal diet without bacterial additives was used as the control group. The experiment lasted for 6 weeks. After the feeding trial, a 14 d Vibrio parahaemolyticus challenge experiment was conducted. Results showed that the final weight, specific growth rate and feed efficiency of shrimp in BD and BV were significantly improved as compared to the control (P < 0.05), especially in BV. The activities of peroxidase (POD), superoxide dismutase (SOD), acid phosphatase (ACP) and phenol oxidase (PO) in the serum of shrimp of three treatment groups were significantly higher than those of the control group (P < 0.05). The activities of ACP, AKP and SOD in the serum of BV were significantly higher than those of BD (P < 0.05). Compared with the control, the relative expression level of proPO, LZM, SOD, HSP70, Imd, Toll, Relish, TOR, 4E-BP, eIF4E1α and eIF4E2 in the hepatopancreas of shrimp of BD was significantly higher than that of the control (P < 0.05). The relative expression level of proPO、LGBP、Imd、Toll、4E-BP and eIF4E2 in the hepatopancreas of shrimp of CD group was significantly higher than that of the control (P < 0.05). The relative expression level of proPO, LZM, SOD, LGBP, HSP70, Imd, Toll, TOR, 4E-BP and eIF4E1α in BV was significantly higher than that of the control (P < 0.05). The relative expression level of SOD, LGBP, Toll and 4E-BP in BV was significantly higher than that of CD and BD (P < 0.05). The challenge test of V. parahaemolyticus revealed that the cumulative mortality of shrimp in three treatment groups was significantly lower than that in the control (P < 0.05). In conclusion, the effects of adding B. subtilis BSXE-1601 and B. velezensis 26.3 in the feed markedly enhanced the growth performance of P. vannamei. Two Bacillus species elicited a superior immune response compared to B.cereus BCXE-01. Three Bacillus species significantly enhanced the resistance against V.parahaemolyticus of P.vannamei.