A probiotic bacterium isolated from the gut of wild shrimp Penaeus monodon rendered maximum
antagonistic activity against shrimp pathogens and was capable of producing extracellular enzymes. The
probiotic bacterium was identified as Bacillus cereus through 16S rRNA sequencing. The lyophilized
B. cereus was supplemented with shrimp basal diet at four different concentrations (0.1e0.4%/100 g feed)
in D1eD4 diets. The viability of probiotic bacterium in the test diets was evaluated during the study
period at various time intervals. The viability ranged from 50.24 1.42 to 180.34 1.30 CFU/g in D1 to
D3 diets on the 30th day, whereas it was slightly declined from 45.23 1.30 to 169.13 1.18 CFU/g
during the 90th day of storage. A control diet (C), devoid of probiotic supplementation was also
simultaneously prepared. During experimentation, P. monodon postlarvae (PL-15) were cultured in individual
one tonne capacity FRP tanks in triplicates provided with equal amount of substratum (clay soil)
and fed with these respective diets at ad libitum for 90 days. Survival was high (82.0 1.60%) in D4 diet
fed shrimp as against a low survival of 65.0 1.33% displayed by control diet fed shrimp. Overall growth
responses inferred that a maximum production of 10.45 0.275 g, SGR of 4.40 0.179% and a better FCR
of 1.27 0.081 were obtained in D4 diet fed shrimp. However, the water quality parameters showed
nonsignificant (P > 0.05) variations among the control and the probiotic treated groups. The tested
immunological parameters such as Total haemocyte count, phenoloxidase activity, respiratory burst
activity, lysozyme activity, plasma protein concentration and bactericidal activity were higher in D4 diet
fed P. monodon, when compared to that of other diets fed shrimp. It is therefore suggested that lyophilized
probiotic B. cereus at a concentration of 0.4%/100 g feed was efficient in stimulating the growth and
immunity in shrimp.