Using pathogenicity challenge test for Assessment of putative Bacillus subtilis as probiotic in juvenile P. indicus

Objective: Sensitivity of juvenile shrimp to 2 putative bacteria strains was examined using in-vitro and in-vivo pathogenicity challenge test to assess as probiotic in juvenile P. indicus. Method & Materials: In-vitro challenge test was carried out on juvenile shrimps (0.1g) using the immersion method. An in-vivo challenge experiment was carried out using the feeding trial method. Bacterial suspension was added to the challenge feed at a concentration of 1010 cells/ ml, except in the control diet. Survival rate during four weeks post challenge was determined weekly. Results & Conclusion: The result of in-vitro pathogenicity tests indicated that exposure to Vibrio parahaemolyticus, induced significant (p<0.05) mortalities in P. indicus within 12 hours at 107 cells/ml and 24 h at 105 cells/ml level. In in-vivo study the survival of juvenile (0.45g) was not affected by the presence of Bacillus in fresh water but, V. parahaemolyticus infected juvenile P. indicus and cause mortality about 78.67% and exhibited disease clinical signs. There were significant differences among control and Bacillus sp tanks with V. parahaemolyticus tanks on the prawn survival (P < 0.05). From this, it was concluded that the putative Bacillus subtilis may be a promising probiotic for juvenile P. indicus.

کلیدواژه ها:

Pathogenicity ، V. parahaemolyticus ، Bacillus sp ، Survival ، Challenge