Isolation And Screening Of PDG-Producing Endophytes From Eucommia Ulmoides Oliv. And Its Culture Optimizing

Eucommia ulmoides Oliv., the only variety in eucommia genus, eucommia family, is one kind of peculiar economic tree in China. It is classified as second class protected tree. So the tree should be protected while fully using the natural resources. Hoping for not destroying E. ulmoides resources while exploiting natural anti-biotic substances, The title has isolated and identified endophytic fungi from E. ulmoides, screened PDG of some strains, and optimizing culture for the strain was also conducted. The results are as follows:Firstly, 122 strains of endophytes were obtained from the skin 7 or above years old Eucommia Ulmoides Oliv., of which 75 strains were fungi, 47 were bacteria. These strains were cultivated in liquid medium in flask to detect their ability to produce PDG. It was found that only 8 strains were able to produce PDG and all these strains were fungi. The highest PDG production was 13.387mg/L.It has been identified that these 8 strains were Phloma, Pythium, Oospora, Tolyposporium, Lateritium.Secondly, the growth curve and the time that the strain produced PDG was given in this article. The study on the 8 PDG-producing strains already screened from Eucommia Ulmoides Oliv. was carried out to obtain one-PDG-highly-producing strain, and the optimizing culture of this strain was also conducted. The growth curve and the best time to produce PDG was obtained in this article.Thirdly, the PDG in submerged fermentation by the strain is strongly influenced by many internal and external factors, namely medium constituents and fermentation conditions, In this study Plackett-Burman Design was undertaken to evaluate the effects of the fourteen factors. By the statistical regression analysis, the significant factors affecting the PDG in submerged fermentation by the strain were determined as follows: soluble amylum , maltose, NH₄Cl, NaNO₃, FeSO₄, KH₂PO₄. In the second phase of the optimization process, a response surface methodology(RSM) was used to optimize the above critical internal factors, and to find out the optimization concentraction levels and the relationships between these factors. By solving the quadratic regression model equation using appropriate statistic methods, the optimal concentration of the variables were determined as: soluble amylum , maltose, NH4Cl, NaNO₃, FeSO₄, KH₂PO₄. The content of the PDG was increased from 13.387mg/L to 29.386mg/L. The experimental data under various conditions have validated the theoretical values.