The effects of Bacillus species probiotics (Bacillus subtilis and B. licheniformis) on the water quality, immune responses, and resistance of whiteleg shrimp (Litopenaeus vannamei) against Fusarium solani infection

Abstract

This study investigated the impacts of water application of a commercial Bacillus species probiotics, SANOLIFE®PRO-W (containing Bacillus subtilis and B. licheniformis), on water quality, digestive enzymes, growth performance, antioxidants, innate immunity, body composition, and resistance of whiteleg shrimp against Fusarium solani infection. A total of 240 animals (2.00 ± 0.07 g) were stocked into twelve 1-m3 concrete ponds and divided into four triplicate treatments. For 56 days, the rearing water was supplemented with Bacillus species probiotic at 0, 0.01, 0.02, and 0.03 g/m3 and defined as control, T1, T2, and T3 groups, respectively. Results revealed that Bacillus species probiotics increased dissolved oxygen and decreased total ammonia, nitrite, and unionized ammonia in the rearing ponds. However, adding probiotic Bacillus to rearing water significantly increased the digestive enzyme (chymotrypsin, trypsin, protease, lipase, and amylase) and growth performance parameters compared to the control. On the other hand, the antioxidant levels of superoxide dismutase, catalase, and glutathione peroxidase were increased significantly, while the malondialdehyde concentrations were decreased significantly compared to the control. Furthermore, Bacillus probiotics boosted the innate immunity of shrimp manifested by increased activities of lysozyme, prophenoloxidase, respiratory burst, and the total hemocyte count compared with the control treatment. Of interest, shrimp mortalities decreased after F. solani infection to 35% in the T3 group compared to 100% in the control group. In conclusion, water application of Bacillus species probiotics, especially at 0.02 and 0.03 g/m3, improved the water quality, welfare, and resistance of whiteleg shrimp to F. solani infection.