Screen Strains Which Are Against Vibrio Splendidus And The Study On Antibacterial Substances

According to the latest statistics, Apostichopus japonicus breeding has become an economic pillar industry in Liaoning province, currently, the Apostichopus japonicus breeding mainly use of antibiotics for the prevention and treatment of Apostichopus japonicus disease, the improper adding and residues of antibiotics can do harm to the human health and the safety of the environment. The flora of Apostichopus japonicus body has the effect of antagonistic action and plays an important role in the prevention of some diseases. Maintaining the stability of surface bacteria plays an important role to inhibit pathogen infection, by using the biological control method can not only reduce the production cost, but also improve the safety and health of Apostichopus japonicus products.Antagonistic bacteriums were screened from the microorganisms which were isolated from the surface and the intestinal of Apostichopus japonicas in cross-streaking method and filter paper method, these strains were maintained in the laboratory. There were 7 antagonistic bacteriums against Vibrio splendidus in filter paper method, and 6 in cross-streaking method. According to the strength of the antagonistic activity of bacteria surface, we found that the strain Bacillus subtilis CG Its extracellular metabolites can inhibit the Apostichopus japonicus skin disease which is caused by Vibrio splendidus. It shows that the optimum growth temperature of Bacillus subtilis CG to produce bacteriostatic activity is 25?,and the optimal growth pH is 6.0-7.5, the optiun growth time is 22 h, it can use a variety of carbon sources, and the optimum carbon source is glucose, it can only make use of organic nitrogen source, but not inorganic nitrogen source, the optimal nitrogen source is peptone. The antagonistic bacteria competed nutrients and living space with Vibrio splendidus and produced antibacterial substances, these two effects are a synergistic effect.The strain of Bacillus subtilis CG was isolated and purified from the surface of Apostichopus japonicus. The substance was extracted by n-butanol (developing solvent volume ratio was chloroform:methanol:formic acid= 6:4:0.1), the substance was a medium polar molecules. TLC detection, color reaction, and infrared spectroscopic analysis were used to detect. It was supposed that the antibiotic substance was aminoglycoside compound. Using aminoglycoside compound, gentamicin, as the standard, determine the titer of antagonistic substances in paper method, we learned that the bacteriostasis potency of the antagonistic substance was 2855 u/mL.