Screening And Identification Of Marine Symbiotic Microorganisms And Study Of Its Antimicrobial Active Products

As the problem of abuse of antibiotics, microbial drug resistance is rapidly increasing leading to a centain extent that it is harmful to human health. The effect way to handle this problem is to search for new bacteriostatic activity substances. Therefore, extremely abundant microorganism resource and unique environment of marine has become one of the most important source for screening antibacterial preparation. It is an important primary work to screen strains with bacteriostatic activity from marine microorganisms.The strain B132with a broad antimicrobial spectrum was isolated from136marine bacteria which were screened from the mud in the intestine of the sea cucumber. The strain inhibits not only G+, but also G-. The strain B132showed an obvious antibacterial activity and good genetic stability, so it has a further development value. On the basis of morphologic-al identification and16S rDNA sequence analysis, the strain B132was identified as Bacillus subtilis.The mixed antimicrobial substances were extracted from Bacillus subtilis B132. The range of protein molecular weight, the effects of temperature, pH, ultraviolet radiation, organic solvents on biological stability, and the characteristics of enzyme production were investigated. The results showed that the bacteriostatic activity substance is probably a protein by hydrolysis of proteinase K. The best bacteriostatic activity from the protin was the extraction with60%saturated (NH4)2SO4. The study of ultrafiltration indicated that the range of protein molecular weight is greater than50kD. The fermenting broth of the strains B132could endure high temperature, and have a wider range of pH. The ultraviolet and organic solvents had little effect on crude antagonist extraction. The strain B132has ability of hydrolyzing protease, cellulose, amylase through screening of the tablet of protease, CMC-Na and amylase.By the single factor and the orthogonal design, the optimal fermentation condition of the strain B132was determined. The result showed that the optimal fermentation condition consist of intital pH=8, the inoculation with5%, the incubation temperatures at28℃for48h. And through the date of orthogonal design, we can find primary and secondary factors which effect the antibacterial activities of the strain B132.