Gut<i>Lactobacillus</i>sp. bacteria as probiotics for<i>Portunus pelagicus</i>(Linnaeus, 1758) larviculture: effects on survival, digestive enzyme activities and water quality

Abstract

Abstract In this study, the effects of indigenous probiotic, Lactobacillus rhamnosus, as an additive to water in Portunus pelagicus larviculture was investigated on survival rate, digestive enzyme activities and water quality. All experiments were triplicated and designed with three different administrations of probiotic 1.0 × 106 cfu mL−1 (T-1), 5.0 × 106 cfu mL−1 (T-2) and 1.0 × 107 cfu mL−1 (T-3) added daily and one control without any probiotic. The supplementation of the probiotic significantly (p < 0.05) increased survival rate for all treatments over the controls. Highest survival rate (10.0 ± 0.9%) of larvae was achieved in T-2. Addition of probiotic bacteria affected the bacterial load (cfu mL−1) in rearing water. The specific activities of protease and amylase enzymes in probiotic treatments were significantly higher (p < 0.05). The highest specific activities of protease (0.17 ± 0.01 U mg−1 protein) and amylase (0.36 ± 0.02 U mg−1 protein) were determined in treated group T-2, respectively. Addition of probiotic affected the pH and nitrogen content of rearing water. The results of this study suggest that the indigenous L. rhamnosus added to rearing water at a certain concentration significantly enhanced survival rate, measured digestive enzyme activities and improved the water quality of P. pelagicus larvae. Keywords: indigenous Portunus pelagicus probioticdigestive enzymes Acknowledgements This study was mainly supported by the Fisheries Department, Government of Sindh, Pakistan under capacity building project and partially by the Ministry of Science, Technology and Innovation (Science Fund), Government of Malaysia under grant Vot. No. 52042. The authors thank the Director and the staff of the Institute of Tropical Aquaculture (Aquatrop) and marine hatchery for their help. The corresponding author thanks Mr G.M. Mahar, Director General Fisheries and Mr G.M. Wadahar, Director Fisheries Sindh Inland, Government of Sindh, Pakistan for their extended support for this study.