| Since Fleming found penicillin from fungi in 1929, microorganisms became the rich source for bioactive substances. During the past seven decades, thirty to fifty thousands natural products were found and more than ten thousands of them showed various bioactivities and of which more than eight thousands were identified as anti-bacterial or anti-tumor agents. However, with the spread of drug-resistance pathogenic microorganisms, the appearance of new pathogenic microorganisms, as well as the increase of cancer and cardiovascular diseases, it has become a current emergency mission to look for new sources of active substances. So the scientists cast their lights on the sea, a large less good exploited resource of natural products. In 1964, Schmeer, as the first one, isolated clamtin, a kind of polysaccharide with anti-tumor activity from clam. Since then the door of getting active substances from the sea was opened and in the succeeding decades years, many countries including USA, Japan, England, Frence, Russia, etc, of the world march on the sea one after another. Sevral scientific projects were focused on the exploiting marine microbial drugs, including Marine Biology Technology Project, the Blue Stone Project, Marine Organism Developing Project, etc. The marine depends on its low temperature, high pressure, less nutrition, thick salt, etc. makes the microorganisms live in it produce natural product with novel and various structure and with particular pharmaceutical activities.Among our four sea area, the Bohai Sea, the Yellow Sea and the South China Sea have been researched much of their microbial resources, but there is little report about large scale and large extent resource investigation, active strains screening of the China East Sea area. In the May of 2003, our team collected 28 sea water and sea sediment samples 35 nautical miles far from the seacoast of the East China Sea, and1043 microorganism cultures were isolated from them with dilution and plate streak technique. With Pyricularia oryzae as primary activity screening model, 216 cultures with good inhibition on Pyricularia oryzae were obtained. In this dissertation, a strain with best activity, F8712, was genomic identified based on its 16S rDNA. Various physiological and biochemical aspects were characteried. Its optimum fermentation condition was studied. After large scale fermentation, its secondary metabolites were isolated and purified, their structures were elucidated and their bioactivities were also tested in different models.The result of the presentation shows that the strain F8712 was a lower halophilic microbe and its most optimum salt concentration is 2.5%. Further study showed that the activity reachs up to the peak on the condition of 25 ℃, with the shake frequency of 120 r/min and the original fermentation pH value of 6.0, the inoculation dose of 5% (V/V) and harvest at 72 to 96 hours after fermentation. The fermentation medium ingredients include 0.4% of peptone, 0.4% of yeast extraction, 1% of beef cream and 1% of glucose.The 16S rDNA amplification and sequence alignment and evolutionary tree establishment showed that the strain F8712 was most intimate with Bacillus subtilis BFAS on the tree and had a identity of 99.67% with it, so F8712 was identified as Bacillus subtilis The study of physiological and biochemical characteristics also demonstrated that this strain had some same essential sepects with the terrene Bacillus subtilis.According to the optimum fermentation conditions, 30 liter culture broth were harvested. After centrifugation, the thallis were removed, and the broth showed good inhibition ability aganist Pyricularia oryzae, the maximum active dilution was 1:256. The 30 liter broth was extracted by the same volume of Ethyl Acetate and n-Butanol in turn respectively three times, then boiled to dry and 10.3 gram of Ethyl Acetate extract and 48.2 gram n-Butanol extract were obtained. Being checked by Pyricularia oryzae, their minimum active concentration were 7.8 μg/mL and 0.98 μg/mL. The Ethyl Acetate extract were fractionated by silicon column chromatograghy repeatedly, and eluted by the gradient of chloroform and methanol and then be purified by highperformance liquid chromatagroghy (HPLC), 15 compounds were obtained in all. Using nuclear magnetic resonance (NMR) and mass spectral (MS) technology, and complemented with routine physical and chemical methods, 12 compounds were elucidated.They were cyclo (D-Pro-D-Ile), cyclo(L-Pro-L-Val), cyclo (L-Pro-D-Leu), cyclo(L-Val-L-Leu), cyclo(D-Pro-D-Phe), cyclo(L-Ala-L-Ile), cyclo (L-Ala-L-Leu), cyclo(Gly-Tyr) , Uridine , cyclo(L-Pro-L-Ala) , cyclo ( L-Ala-L-Phe ) and cyclo(Gly-Ala). The n-Butanol extract was fractioned by reverse C-18 column, and eluted by the gradient of water and methanol, and then be purified further by HPLC, 13 compounds were obtained. One of them might be cycloundecapeptide, the others seem to be cyclopepetides composed with five to eight amino acids, and their structures are under elucidation at present. The elucidated structures see the Chinese abstract.Using Pyricularia oryzae and other activity demonstration model, complented with reference consultation, we found compound A-l cyclo(D-Pro-D-Ile), A-6 cyclo(L-Pro-D-Leu) and A-11 cyclo (D-Pro-D-Phe) had strong anti-Vibrio anguillarm ability, their MICs were 0.05, 0.12 and 0.03 (J.g/mL, respectively. Compound A-4 cyclo (L-Pro- L-Val) had antibiotic and cytotoxic activity, and Compound A-13 cyclo(L-Ala-L-Leu) had virus-static activity. All of the cyclopepetides showed strong anti- Pyricularia oryzae ability, the MIC<1 \igln\L. The cycloundecapeptide also had some inhibition ability against pancreatic cancer cell 1990 and liver cancer cell hul-7, their ED50 were 21.2 and 32.2 ug/mL, respectively.
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