Recent research shows that Bacillus coagulans has great potential in aquaculture. The strain Bacillus coagulans in the genus Bacillus is a gram-positive bacterium that combines both the Bacillus and LAB (lactic acid) can release stress and survival in the extreme heat condition, and tolerance in stomach acidity, bile salts, and inhibit intestinal pathogenic bacteria.
The present study evaluated the effects of Bacillus coagulans (BC) in different inclusion levels (0 (BO); 1 × 106 (BC1); 1 × 107 (BC2) and 1 × 108 (BC3) CFU g−1 feed) CFU/g feed. Feeding within 56 days, then challenge with Vibrio parahaemolyticus - the main cause of acute hepatopancreatic necrosis disease in shrimp.
At the end of the experiment, the growth rate, feed efficiency, gut morphology, intestinal microflora, immune response and resistance to Vibrio parahaemolyticus infection in white leg shrimp were tested.
After 56 days of conducting of experimental culture, the survival rate ranged from 83.33 to 94.17%, there was no significant difference between the diets (P > 0.05).
Shrimps in the BC2 group showed significantly higher final weights final weight, weight gain rate and specific growth rate compared with the rest of the groups. The lowest FCR was recorded from group BC3, followed by group BC2, BC1 and BO. The results for muscle composition were nearly identical in terms of protein and lipid content except for moisture, which was found to be lower in the probiotic-supplemented treatments than in the control group.
The supplement of probiotics in the diet also affects the composition of the gut microbiota. At the phylum level, Proteobacteria make up the majority of bacteria, followed by Bacteroidetes. At the genus level, the abundance of opportunistic pathogens, such as Vibrio, Tenacibaculum and Photobacterium was significantly reduced (P < 0.05) with the probiotic concentrations increased and the least encountered BC3 group.
In addition, increased probiotic supplements in the diet helped to reduce the amount of Muricauda, Kangiella and Shewanella in shrimp which was observed in the BC3 group. However, the beneficial bacteria Pseudoalteromonas was significantly increased (P < 0.05) in the gut of shrimp fed the BC3 diet (P < 0.05) compared with the other groups including the control.
Compared with the control group, there was a significant increase (P < 0.05) of the groups treated with the active probiotic lysozyme (LYZ), acid phosphatase (ACP), superoxide dismutase (SOD), total protein (TP). ), albumin (ALB) in serum, glutathione peroxidase (GSH-Px) in serum and liver, significantly reduced serum triglycerides (TG) and Malondialdehyde (MDA) in serum and liver.
The probiotic supplement helped to improve the digestibility, thereby increasing lipase, amylase, and trypsin activities and increasing the height, width, and thickness of intestinal villi.
After 14 days of challenge with V. parahaemolyticus, the mortality was significantly lower in the treated groups than in the control group. The highest mortality rate in the control group was 83.3%; 43.3%; 36.7% and 20% are BO, BC1, BC2 and BC3 respectively. Relative survival percentage (RPS%) was highest in BC3 (76%), followed by BC2 (56%) and BC1 (48%). Thereby, it was found that the addition of probiotics enhanced the resistance of shrimp against V. Parahaemolyticus.
In conclusion, dietary probiotic levels of 1 × 108 CFU/g feed (BC3) can enhance growth, gut morphology and gut microbiota, immune response, and resistance to Vibrio parahaemolyticus on Vannamei shrimp.
Reference:
KwakuAmoah et al (2019). Dietary supplementation of probiotic Bacillus coagulans ATCC 7050, improves the growth performance, intestinal morphology, microflora, immune response, and disease confrontation of Pacific white shrimp, Litopenaeus vannamei, ScienceDirect, Fish & Shellfish Immunology, 04/2019.
