Synergistic Effects of Two Probiotic Bacteria on Growth, Biochemical, and Immunological Responses of Litopenaeus vannamei (Boone, 1931)

The beneficial effects of two probiotic bacteria, Bacillus licheniformis and Bacillus megaterium, on growth, biochemical, and immunological responses of Litopenaeus vannamei (Boone, 1931) were evaluated both individually and in combination. A 60 day experimental trial was conducted on 1200 post larvae (PL) of Litopenaeus vannamei divided into four experimental groups, with three replicates of each treatment, and 100 PL in each replicate. The shrimp were fed a commercial diet (32% protein) supplemented with different probiotics. The first treatment included only B. licheniformis @ similar to 1x 10(8) cfu/kg diet (T1), the second consisted of a combination of similar to 0.5 x 10(8) cfu/kg of B. licheniformis mixed with a similar concentration of B. megaterium (T2), and the third had only B. megaterium @ similar to 1x 10(8) cfu/kg diet (T3). The control diet (C) had neither of the probiotic bacteria. Growth performance, biochemical, and immunological parameters of experimental shrimp were measured at 20 day intervals. Probiotic fed shrimp showed significantly higher growth, biochemical, and immunological response than the control. Among the probiotic treatments the mixture of B. licheniformis and B. megaterium (T2) performed better than the individual probiotics alone, indicating the synergistic effect of these two functionally different probiotics.