Host gut-derived probiotic Lactobacillus sp. improves resistance of giant freshwater prawn Macrobrachium rosenbergii against Vibrio harveyi

The present study evaluated the effect of probiotic Lactobacillus sp. against pathogenic bacteria Vibrio harveyi in freshwater prawn Macrobrachium rosenbergii. The bacteria were isolated from the gut of prawn and identified using biochemical and PCR tests. Inoculation of probiotic (9 log CFU/g) and pathogenic bacteria (5 log CFU/g) mixture was employed for in vitro test. The in vivo challenge test was conducted in glass aquaria (45 × 30 × 30 cm 3 ) and also in an earthen pond (70 m 2 , 1 m depth) for 8 weeks, individually. In both cases, only the treatment group was provided probiotic (9 log CFU/g) incorporated feed. Growth, digestibility, and immune response of prawn were determined. Both in the in vitro and in vivo test, V. harveyi growth was found to be reduced significantly at 8 hr (from 5 to 4 log CFU/g) and after 50 days (from 7 to 6 log CFU/g) of probiotic administration, respectively. In the pond, higher growth and better digestibility were found in the treatment group (WG%, 549. 30 ± 40.02%; SGR%, 3.12 ± 0.10%; amylase, 1.23 unit/mg; protease, 2.47 unit/mg) compared to the control group (WG%, 310.77 ± 18.68%; SGR%, 2. 35 ± 0.08%; 0.7 unit/mg; protease, 1.82 unit/mg). The immune response was found to be significantly different ( P