In the present study, commercially available probiotics product, LactoBacil®plus (LBP), which contains a combination of Lactobacillus acidophilus, Lactobacillus rhamnosus, Bifidobacterium longum, Bifidobacterium bifidum and Saccharomyces boulardii was incorporated at 1, 2, 3, 4 and 5% concentrations with basal diet formulated with fish meal, groundnut oil cake, soya bean meal, corn flour, tapioca flour, egg albumin, Cod liver oil and vitamin B-complex with vitamin-C, and fed to Macrobrachium rosenbergii PL for 90 days. The beneficial effects of LBP on the survival, growth, nutritional indices (weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio), activities of digestive enzymes (protease, amylase and lipase), concentrations of biochemical constituents (total protein, carbohydrate and lipid) including profiles of protein, amino acids and fatty acids were determined. In addition to these, gut microbial colony establishment and their biochemical characterization, and the molecular analysis of gut bacterial diversity through 16s rDNA were also done. The survival, growth, nutritional indices, activities of protease, amylase and lipase, concentrations of total protein, carbohydrate and lipid, level of essential amino acids and fatty acids (linoleic and ecosapentanoic acid) were found to be significantly (P<0.05) improved particularly at 4% LBP incorporated diet fed prawns when compared with control. The LBP incorporated feed fed prawn showed increased staining intensity of 36, 29 and 18 kDa protein bands when compared with control. Presence of Bacillus spp., Pseudomonas spp., Escherichia coli, and Streptococcus spp., was deducted in the gut of control prawns. In the gut of experimental prawns in addition to L. acidophilus, L. rhamnosus, B. longum, B. bifidum and S. boulardii the presence of E. coli was also deducted. However no Pseudomonas sp., was deducted in the gut of experimental prawns. The bacterial consortium of control and experimental prawn guts showed 98% and 93% similarity respectively with Ralstonia (genes of proteobacterium). This study revealed that the identified gut microbes were differed from originally incorporated probiotics and unidentified bacterial species was present. This needs further clarification. In conclusion, the LBP at 4% was found to be beneficial for survival, growth and production of M. rosenbergii. Therefore, this can be recommended to incorporate in aqua feed formulations for the sustainable development of Macrobrachium culture.
