Abstract
The shrimp Penaeus monodon was used for the isolation of digestive enzyme producing host-associated probiotic bacteria. Gut was isolated from a healthy animal completely and morphologically different bacterial isolates were screened for the production of hydrolytic enzymes, such as, protease, amylase, lipase and cellulases. Based on their ability to produce enzymes, the potent probiotic bacteria were identified as Bacillus subtilis and B. licheniformis and these two were used for the preparation of probiotic diet for experimental trials. Probiotic diet was prepared by mixing the shrimp feed with 2 g probiotic/100 g artificial diet (F1), 4 g/100 g (F2), 6 g/100 g (F3), 8 g/100 g (F4) and 10 g/100 g (F5). Juvenile shrimp was fed with probiotic and control diet for a period of 7 weeks at 5 and 8% body weight for the first 3 and 7 weeks, respectively. After seven weeks, whole gut was dissected out and protease activity was estimated as 145 ± 12.3 U/g in control animal and increased as 710 ± 15.2 U/ g in F5 feed groups. Amylase activity was 139 ± 10.4 U/g in control and increased as 209 ± 13. 3 U/g in F5 group. Cellulase activities were 171 ± 9.3 in F5 groups and the control group showed only 102 ± 12.4 U/g. Lipase activity was 78 ± 3 U/g in F1 groups and it increased as 85 ± 5 U/g in F3 groups. These findings indicate the potential of host-associated bacteria to enhance the production of enzymes in the gut of juvenile P. monodon.