Effects of Bdellovibrio and Like Organisms on Survival and Growth Performance of Juvenile Turbot, Scophthalmus maximus

In this study, the impact of Bdellovibrio and like organisms (BALOs) on juvenile turbot rearing was investigated in a static water rearing system with weekly partial change of water. A 60-d-long rearing experiment showed that, compared with control, survival rate, percent weight gain, percent length gain, and average daily growth were 92 +/- 2.8%, 387.1 +/- 4.6%, 78.6 +/- 1.5%, and 1.87 +/- 0.79g/d, respectively, significantly higher than those in the control, viz., 81 +/- 3.2%, 248.2 +/- 5.3%, 56.7 +/- 2.1%, and 1.16 +/- 0.68g/d, respectively. Water quality results demonstrated that no significant difference (P>0.05) was observed between test and control with the addition of BDW03. Compared with the control, total culturable bacteria and total vibrio numbers in rearing water and in intestines were significantly (P<0.05) reduced by 0.8-1.4 log CFU/mL/ log CFU/g, with the addition of BDW03. Furthermore, denaturing gradient gel electrophoresis profiles in rearing waters collected at a 1.5-d interval over a week revealed that BDW03 simplified bacterial community structures with time, and some vibrios disappeared with the addition of BDW03. To the best of our knowledge, this is the first report that BALOs can promote growth and survival of juvenile turbots and be beneficial to coldwater fish aquaculture at the production level.