Effects Of Vibrio Alginolyticus And Bacillus Sp. On Growth, Immune Parameters And Anti-disease Ability Of Litopenaeus Vannamei

In recent years as the requirements of health and safety of cultivation gradually increased, the provisions of the drugs in aquaculture and increasingly strict restrictions. Probiotics is becoming more and more important in aquaculture. Probiotics are made of one or several kinds of bacteria products, usually added to the water body directly or added to the feed. Probiotics have the functions of regulation of water quality, increase production of farmed animals, inhibit bacteria growth, reduce disease and so on. Mechanisms of probiotics effect is considerde to have the following several aspects:1.Inhibition the growth of pathogen in the environment and animals by antagonism.2. Stimulation of farmed animals immunity, improve the disease resistance.3.Secrete enzymes, amino acids, polysaccharide, etc to promote the growth of animal metabolism, increase production.4By absorbing ammonia nitrogen, nitrate nitrogen in water, as well as the secretion of polymer adsorption heavy metal particles to improve water quality.There has been many studies on feeding bacteria can enhance immunity of aquatic animals, but the mechanism remains unclear for bacterial immune regulation. There is now considered through two main aspects: one is by changing the intestinal microflora, reducing the number of bacteria to reduce the incidence of animals, while bacteria may be able to improve the level of immunization of animals by animals is absorbed by a substance to increase the animal’s resistance to disease.1. Effects of different bacteria and broken bacteria on growth, digestive enzyme activities, immune parameters and anti‐disease ability of shrimp Litopenaeusvannamei A49‐day feeding experiment was conducted to evaluate the effects of different bacteria and broken bacteria on digestive enzyme activities, enzymes of peroxidase activity(POD), superoxide dismutase activity(SOD), phenoloxidase activity(PO), antibacterial activity and immunity of shrimp Litopenaeusvannamei with initial body weight of (3.58±0.32)g． Shrimps were fed five different diet treatments: control (basic shrimp pellet), or living Bacillus (basic pellet with Bacillus sp. of BZ5strain supplemented), or living Vibrio (with Vibrio alginolyticus of VZ5strain supplemented), or broken Bacillus (with broken Bacillus sp. supplemented), or broken Vibrio (with broken Vibrio alginolyticus supplemented). The bacteria dosage supplemented in dietary was108CFU/g. Results show that:1) No significant difference in growth rate and survival rate of five treatments.2) Diet with supplementation could improve the activities of protease in intestine (P<0.05). Diet with supplementation could improve the activities of amylase in intestine when farmed25days (P<0.05). After49days, the amylase level in intestine of Vibrio treatment and broken Bacillus treatment is significantly higher than the control group. Intestinal digestive enzymes of broken Bacillus treatment are higher than other treatment groups which of Bacillus treatment is lower than other treatment groups.3) After49days, SOD of Vibrio treatment was significantly improved, SOD, PO and antibacterial of broken Vibrio treatment were significantly improved, Phenol oxidase of Bacillus treatment were significantly higher than that of control group, antibacterial enzyme levels dropped significantly, SOD and PO of were broken Bacillus were significantly improved, antibacterial enzyme levels dropped significantly.4) Attacked by WSSV, the length of half lethal time: broken Bacillus treatment> broken Vibrio treatment> Vibrio treatment> Bacillus treatment. The results suggested that the diet supplemented with Vibrio and Bacillus could improve the level of Intestinal digestive enzymes and immunity of shrimp, can improve the disease resistance, and broken Vibrio showed better effects on immunity, broken Bacillus showed better on digestive enzymes and disease resistance.2. Effects of different components of Bacillus on growth, mmune parameters and anti‐disease ability of shrimp Litopenaeusvannamei A60‐day feeding experiment was conducted to evaluate the effects of living Bacillus, different components of Bacillus on digestive enzyme activities, enzymes of peroxidase activity(POD), superoxide dismutase activity(SOD), phenoloxidase activity(PO)and immunity of shrimp Litopenaeusvannamei with initial body weight of (1.45±0.06)g． Shrimps were fed five different diet treatments: control (basic shrimp pellet), or living Bacillus (basic pellet with Bacillus sp. of BZ5strain supplemented), or extracellular products of Bacillus (with extracellular products of Bacillussp. supplemented), or cell wall ofBacillus (with cell wall ofBacillus sp. supplemented), or intracellular products of Bacillus (with intracellular products of Bacillussp. supplemented). The bacteria dosage supplemented in dietary was108CFU/g. Results show that:1) No significant difference in growth rate of five treatments. The survival rate of living Bacillustreatmentis significantly lower than other treatments, but the production has no significant difference from other treatments.2) SOD, POD, PO activity of living Bacillustreatmentis significantly higher than control treatment.POD activity Intracellular treatment has been in a high level the same with living Bacillustreatment, the activity of SOD and PO is low at the beginning, at60days, the level of SOD and POD were higher than in living bacterium group, PO activity is lower compared with the living Bacillustreatment(P<0.05). POD of extracellular treatmentis significantly higher than control group and is higher than the living Bacillustreatment at60days, while the SOD activity has no significant differencewith control treatment at the end of theexperiment. PO activity of the extracellular treatment is significantly higher than control treatment and lower than the living Bacillus treatment(P <0.05). SOD activity of cell wall treatment significantly increased in the mid breeding, however in the late breeding decline and significantly lower than control treatment (P<0.05).4) Attacked by WSSV, the length of half lethal time: intracellular treatment>living Bacillus treatment>cell wall treatment>extracellular treatment. The results suggested that the diet supplemented with intracellular products of Bacillu ssp. could improve the level of immunity and the disease resistant of shrimp3.Extraction of intracellular polysaccharide of Bacillussp. and Vibrio alginolyticus, purification and identification of traits of intracellular polysaccharideThe crude polysaccharidewas extracted from intracellular productsof Bacillussp. and Vibrio alginolyticus.6hours via80℃water and alcohol sedimentation. Protein was removed using Seveg method. Polysaccharide from Vibrio alginolyticus and from Bacillussp. was obtained after dialysis and lyophilization. Determine the content of polysaccharide, computing of intracellular polysaccharide content in the feed in breeding experiments.V0and B0was further purified with cellulose column chromatography, and using high performance liquid chromatography (HPLC) determination of the molecular weight. The results showed that: Vibrio polysaccharide polysaccharide content was65.79%, bacillus polysaccharide polysaccharide content was83.53%. V0and B0had reducing power and scavenging effect on DPPH and hydroxyl free radicals and B0was better than V0...