Kumar, P.; Kaur, V.I.; Tyagi, A., and Nayyar, S., 2019. Probiotic potential of putative lactic acid bacteria isolated from the fish gut: Immune modulation in Labeo rohita (Ham.). In: Jithendran, K.P.; Saraswathy, R.; Balasubramanian, C.P.; Kumaraguru Vasagam, K.P.; Jayasankar, V.; Raghavan, R.; Alavandi, S.V., and Vijayan, K.K. (eds.), BRAQCON 2019: World Brackishwater Aquaculture Conference. Journal of Coastal Research, Special Issue No. 86, pp. 119–127. Coconut Creek (Florida), ISSN 0749-0208.

Aquaculture, growing with rapid pace is facing challenges from disease outbreaks, poor water quality and environmental stress. Use of antibiotics to control the disease is causing great concern in terms of environmental pollution and antimicrobial resistance genes. Probiotic treatment can be an alternative strategy to reduce the use of harmful chemicals and antibiotics. A feeding trial was conducted to evaluate the effects of probiotic (Lactobacillus plantarum FLB1, isolated from the intestine of Indian major carp, Labeo rohita) through dietary supplementation on the immune status and disease resistance of L. rohita fingerlings. Fingerlings (mean body weight 6.0±0.6g) of L. rohita were distributed randomly into six treatment groups in triplicate and fed with graded probiotic concentration. Water quality parameters with respect to temperature, dissolved oxygen, pH, alkalinity and ammonical nitrogen did not differ significantly (p ≤0.05) in different treatments, whereas the difference for total hardness and phosphate were significant among (p ≤0.05) treatments, but well within the optimum range. Hematological, biochemical and antioxidants parameters were studied at 30, 60 and 120 days post-feeding to check the immune status of fish. Significant changes (p ≤0.05) were observed in all treatments (higher in T6) in terms of elevated levels of TEC, TLC, Hb and PCV along with significant increase in total serum protein, albumin, globulin, serum lysozyme and myeloperoxidase activities during whole experimental period as compared to control with maximum rise at 60 days, while liver enzymes ALT and AST showed a declining trend. Control and probiotic fed fishes were challenged with a pathogenic strain of Aeromonas hydrophila post 120 days feeding, which showed higher survival in all probiotic treated groups.