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Evaluations of lactic acid bacteria as probiotics for juvenile seabass Lates calcarifer
Author(s) -
Rengpipat Sirirat,
Rueangruklikhit Thosaporn,
Piyatiratitivorakul Somkiat
Publication year - 2008
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2007.01864.x
Subject(s) - aeromonas hydrophila , biology , lates , streptococcus iniae , aquaculture , lactic acid , aeromonas salmonicida , juvenile , microbiology and biotechnology , juvenile fish , bacteria , veterinary medicine , fishery , fish <actinopterygii> , ecology , genetics , medicine
Lactic acid bacteria (LAB) were isolated from adult, wild‐caught and farmed seabass ( Lates calcarifer ) intestines for evaluation as possible probiotics using the well agar diffusion method. Five LAB isolates (designated as LAB‐1–5) were found to inhibit Aeromonas hydrophila , a known seabass pathogen. Median lethal concentrations (LC 50 ) of A . hydrophila on juvenile seabass were measured in aquaria. Median lethal concentration values of 7.76, 7.47 and 7.26 log 10 CFU mL −1 for 72, 96 and 120 h, respectively, were found. Juvenile seabass (0.6±0.2 g) were cultured in aquaria and fed individual LAB‐1–5 fortified feeds with 7 log 10 CFU g −1 LAB. Seabass fed LAB‐4 fortified feed had significantly greater growth ( P <0.05) than fish fed other feeds. Seabass fed LAB‐4 also had greater survival, but this was non‐significant ( P <0.05). Challenge tests of LAB‐4 fed seabass with A . hydrophila at ∼7 log 10 CFU mL −1 yielded significantly greater survival compared with control seabass ( P <0.05). Aeromonas hydrophila infections in seabass were confirmed by observing disease manifestation and by immunohistochemistry techniques. LAB‐4 was preliminarily identified using lactic acid analysis, biochemical and physical characteristics. It was further identified using 16S rDNA sequencing. LAB‐4 was identified as Weissella confusa (identity of 99%). GenBank accession number for the 16S rDNA sequence for LAB‐4 was AB023241.