FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

The sensitivity of the probiotic Bacillus licheniformis FRI MY-55 to low pH levels and high bile concentrations was tested, as were the effects of the probiotic and its lactosucrose and levan products on the growth performance, digestive enzymes, and viable bacterial counts in the intestines of orange-spotted grouper (Epinephelus coioides). Bacillus licheniformis FRI MY-55 was able to survive in pH 2.5 and 1.0% bile salt. Orange-spotted grouper specimens were fed (1) a control diet, (2) a diet supplemented with B. licheniformis FRI MY-55 (107 CFU/g) + lactosucrose (0.15%) culture medium, or (3) a diet supplemented with B. licheniformis FRI MY-55 (107 CFU/g) + levan (0.15%) culture medium for up to 10 weeks. The final weights and percent weight gains of the spotted grouper specimens fed the diet supplemented with B. licheniformis FRI MY-55 + lactosucrose culture medium and those of the specimens fed the diet supplemented with B. licheniformis FRI MY-55 + levan culture medium were higher than those of the control group specimens, but the differences with the control group were not statistically significant (p> 0.05). There were also no statistically significant differences in the feed conversion rate (FCR) between the experimental groups and the control group (p> 0.05). However, the protease and lipase activities in the digestive tracts of the fish fed the diet supplemented with B. licheniformis FRI MY-55 + lactosucrose culture medium and those fed the diet supplemented with B. licheniformis FRI MY-55 + levan culture medium were significantly increased over those in the digestive tracts of the control group fish (p< 0.05). In contrast, the amylase activities in the digestive tracts of the experimental feed groups were not significantly increased over those in the digestive tracts of the control group fish (p> 0.05). The Vibrio spp. counts in the intestines of the groupers in both experimental groups were significantly decreased compared to those in the digestive tracts of the control group fish. Overall, the results of this study indicate that dietary B. licheniformis FRI MY-55 and its lactosucrose and levan products could provide an effective means for enhancing the activities of the digestive enzymes of orange-spotted grouper.