THE EXPRESSION OF MYOSTATIN PROPETIDE IN BACILLUS SUBTILIS AND ITS EFFECT ON THE GROWTH OF MACROBRACHIUM NIPPONENESE

Myostatin propetide (MSTNpp) of Macrobrachium nipponenese was expressed in Bacillus subtilis and its effect on the growth and creatine kinase activity was investigated. The MSTNpp gene sequence was optimized to synthesize BsMSTNpp according to the B. subtilis preference codon, and the recombinant expression plasmid pGJ105-BsMSTNpp was obtained. After the transformation and fermentation of recombinant B. subtilis, the supernatant was collected and identified by Western blot. The results showed that the molecular weight of the recombinant protein was 36.0 kD. The level of recombinant BsMSTNpp increased over time, and the expression level at 100h was 10 times than that in 24h. To verify the biological activity of the recombinant BsMSTNpp, the healthy freshwater shrimp with an average body weight of 1.52 g and average body length of 4.55 cm were randomly divided into 4 groups with 3 replicates per group and 200 shrimps per replicate for a 30d trial. The experimental group 1 and experimental group 2 were fed the basal diet supplemented with recombinant pGJ105-BsMSTNpp at the dose of 0.5×10⁶ CFU/g and 1.0×10⁶ CFU/g respectively. The control group 1 was fed the basal diet, and the control group 2 was fed the basal diet with pGJ105 at the dose of 1.0×10⁶ CFU/g. The results showed that the growth ratios of the experimental groups were significantly higher than that of the control group 1 (P<0.05), and there was no significant difference between experimental groups and the control group 2. The creatine kinase activities of the experimental groups were higher than those of control groups (P<0.05). The results revealed that recombinant BsMSTNpp could enhance the activity of creatine kinase to improve the myocyte proliferation and differentiation to increase the muscle growth rate of Macrobrachium nipponenese. The results provide technical support to study the function of MSTNpp and its application in shrimp aquaculture.