Effects Of Probiotics On Growth,Immunity,Gut Flora And Differential Gene Expression Of Litopenaeus Vannamei

Taking Bacillus subtilis and Rhodotorula marine as feed additives,the growth index, digestive enzyme activity,antioxidant enzyme activity,gut microbiota and differential gene expression of Litopenaeus vannamei were well studied.The experiment was divided into 4 treatment groups,three parallel groups in each group.20 shrimps were placed in each group,the total number of shrimp was 240.The shrimps were fed with ordinary shrimp diets、supplemented with Bacillus subtilis(1.30×10~8CFU/g)of ordinary pellets、supplemented with Rhodotorula marine(1.36×10~8CFU/ml)of ordinary pellets and the mixed ordinary pellets with Bacillus subtilis(1.30×10~8CFU/g)and Rhodotorula marine(1.36×10~8CFU/ml).After rearing for 56 days,the experimental shrimps were challenged with Vibrio harvey at a concentration of 2.86×10~8CFU/ml.The results showed that the growth,digestion and immunity of the shrimps were significantly improved.In the supplemented with Bacillus subtilis(1.30×10~8CFU/g)of ordinary pellets group,the food conversion rate and survival rate of L.vannamei were significantly improved,so as the activities of the liver protease,superoxide dismutase,alkaline phosphatase.The survival rate,the activities of liver amylase,lipase,superoxide dismutase,acid phosphatase and alkaline phosphatase of the L.vannamei group were significantly increased.And the specific growth rate,food conversion rate,survival rate,weight gain rate,food intake,protease,amylase,lipase,superoxide dismutase,acid phosphatase and alkaline phosphatase were significantly increased,too.In terms of disease resistance,the experimental shrimp were injected intramuscularly with high concentrations of Vibrio harvey.Compared with the control group,the time of death after challenge was delayed by 1h.In terms of intestinal flora,the abundance of intestinal flora in the group supplemented with Rhododendron marine was significantly better than the other three groups.In terms of differential gene expression,transcriptome sequencing and bioinformatics analysis were performed on the shrimp liver tissue samples of the mixed group of Bacillus subtilis and Rhodotorula marine.In the GO enrichment analysis,the differentially expressed genes were mainly enriched in bological process,cell group and molecular functions.The metabolic pathways with higher enrichment in the differential gene KEGG signaling pathway are:cardiac muscle contraction(Cardiac muscle contraction),adrenergic signaling in cardiomyocytes(Adrenergic signaling in cardiomyocytes),purine metabolism(Purine metabolism)and progesterone-mediated oocyte maturation(Progesterone-mediated oocyte maturation)metabolic pathways.Therefore,compared with the control group,Litopenaeus vannamei responded explicitly by regulating its own gene transcription and expression to improve growth rate and immunity.