Probiotic Strain Lactobacillus plantarum GCLP4 Derived From the Gut of Ctenopharyngodon idella Modulates Growth, Digestive Enzymes and Immune-Biochemical Parameters of Labeo rohita Fingerlings

The present study was carried out to isolate, identify, and characterize bacterial probiotic strain from the gut of Ctenopharyngodon idella (Grass carp) and then to study its effect on growth, digestive enzymes and immunity of Labeo rohita fingerlings. A total of 6 gram-positive bacteria belonging to the genus Lactobacillus spp. (3), Bacillus spp. (2) and Staphylococcus spp. (1), were identified biochemically. Based on the biochemical results, the isolate GCLP4 was selected for molecular confirmation and BLAST analysis showed maximum homology with Lactobacillus plantarum (100% ident). Fish were fed for 60 days with diet containing 0 (T0), 10⁵ (T1), 10⁷ (T2), 10⁹ (T3) cfu/g diet of L. plantarum GCLP4 and 10⁵ (T4) of commercial probiotics. Results shows that supplementation of GCLP4 had significantly (p < 0.05) improve weight gain (%), specific growth rate (SGR) and feed conversion ratio (FCR) of L. rohita with better values in T3 group. The immunological parameters (white blood cell, red blood cell, haemoglobin, total protein, albumin and globulin were significantly higher (p < 0.05) with 10⁷ and 10⁹ Lactobacillus GCLP4 cfu/g diet. The digestive enzyme activities (protease, amylase and lipase) were significantly (p < 0.05) higher, particularly, with 10⁹ Lactobacillus GCLP4 cfu/g of diet. All the groups supplemented with GCLP4 including the commercial probiotics have lower (p < 0.05) activities of serum transaminase enzymes along with lower (p < 0.005) level of glucose as compared to the control group. The results of the study collectively suggest that dietary L. plantarum GCLP4 at 10⁹ cfu/g is an effective probiotic obtained from grass carp having potency to promote growth, digestive enzymes and immune-biochemical indices of L. rohita fingerlings in present culture condition.