| Since Fleming discovered penicillin, more than 350 kinds of antibiotics have been used in clinic, which makes many epidemic diseases controlled. However, people must find new drug continuously because of the wide use of antibiotics and the emergence of bacterial drug resistance.Biological resources in land once were the main source of antibiotics. However, with the research going on, it is becoming more and more difficult to find new antibiotics from biological resources in land. Sea and ocean has particular environments, so marine organisms have more biodiversity than terrestrial ones. Marine organism is becoming one of the hotspots of the new drug research in the world.542 marine microorganic strains were isolated from 5 samples of marine sediments and 2 samples of waters in East China Sea. 58 strains were randomly selected and had been amplified by polymerase chain reaction(PCR) technique. ARDRA with enzymes Hinf I revealed 12 operational taxonomic units (OTU) which were dominated by 0TU5 group accounting for 19 isolates and OTU7 group accounting for 11 isolates. The biodiversity of isolates from these two dominant 0TU groups was further investigated by a genomic fingerprinting technique, ERIC-PCR. The results indicated that there were 12 different ERIC-PCR types present among the 0TU5 group and only 4 among the OTU7 group, The data indicated rich diversity profiles of marine microorganism in the East China Sea.XB16, which was isolated from marine sediments in East China Sea, is halophilic microorganisms and its optimum salt concentration is 2. 5% of NaCl, agar diffusion method showed the metabolities of the strain had prominent bioactivity inhibiting Bacillus subtilis , and the antibacterial bioactivity can not be lost after screening again. The sequence of 16S rDNA from XB16 strain was compared with those in database. The evolutional distance was calculated and phylogenetic tree was drawn based on the sequence data. Based on the test result, XB16 were classified into Bacillus subtilis.The fermentation condition have been studied, the fermentation medium includes 4% of glucose, 4. 0% of peptone, 4% of Yeast Extraction, 10% of beef cream. The results showed the optimum fermentation condition were 48 hr of inoculation age, 100 hr of the fermentation time and an initial pH of 6. 0 -6. 5, the best culture condition were 48 hr of inoculation age, 6% of inoculation doses, 250-ml Erlenmeyer flasks containing 60ml of fermentation medium , 130rpm of the oscillation frequency, 25°C of the culture temperature, 250-ml Erlenmeyer flasks containing 60ml of fermentation medium , pH6. 5 of the fermentation medium, 100 hr of the fermentation time. Under that condition the strain can produce the most concentration of the bioactive compounds.The physical and chemical properties of the antibacterial compounds have been studied. The results showed that the bioactive substance has heat stable, acidity and weakly alkali stable, while under strongly acidity and strongly alkali condition the bioactive substance will be lost. When fermentation broth were heated in 80°C for 1 hour, it still is bioactive. It can be dissolved in methanol, Ethyl Acetate solvent, it can not be dissolved in Chloroform, Petroleum ether.Using method of TLC bioautography and filter-paper disc agar diffusion method, bioactivity—guided isolation was followed for the whole process of isolation and purification. Organic solvent has been applied for the liquid phase extraction of fermentation broth. The bioactive compounds, produced by the secondary metabolism of XB16, were isolated and purified by common silica and reverse-phase high performance chromatography. Three kinds of compounds, which inhibited Bacillus subtilis, were obtained. Every kind includes 1 main component, 3 main ones and 3 main ones respectively.
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