Growth, feed efficiency, body muscle composition, and histology of flounder (Paralichthys olivaceus) fed GH transgenic Synechocystis

Effects of transgenic Synechocystis sp. PCC6803 (SYN) containing flounder growth hormone gene on survival, growth, feed efficiency, muscle composition and histology of flounder were assessed in a 7-week feeding trial. 180 fish (weight 20.0 ± 2.05 g, length 11.8 ± 0.81 cm) were randomly distributed into four treatments with three replicates each. The four treatments were (1) Control 1 (fed with commercial diet); (2) Control 2 (fed with commercial diet supplemented with 2.0% non-transgenic alga); (3) LD (commercial diet with low dose of transgenic SYN); and (4) HD (commercial diet with high dose of transgenic SYN). Fish were reared in twelve 50 l indoor aquaria supplied with 17.0–19.0 °C seawater. In each aquarium, fish were hand fed twice a day to apparent satiation. Weight specific growth rate (SGR) of Control 1, Control 2, LD and HD groups were 0.58 ± 0.05, 0.59 ± 0.05, 0.69 ±0.04 and 0.74 ± 0.07, respectively. Body weight in groups LD and HD were increased 32.09% and 49.04% respectively than that of Control group 1. Body length and feed conversion ratio were also proved to be increased (P < 0.05) by the transgenic alga. However, compared to the controls, differences in feed consumption and muscle composition were not evident. Furthermore, apparent alterations in histological structure of stomach, intestine, liver, spleen and kidney of the fish fed with transgenic alga were hard to find. It could be concluded that transgenic Synechocystis sp. PCC6803 containing Paralichthys olivaceus GH gene is an efficient growth promoter and a biologically safe feed additive for fish.