Studies On Fermentation Conditions And Antibiotic Substance Of Bacillus Subtilis TU100

Antagonistic bacterial strain, Bacillus subtilis TU100, which was isolated from the rhizosphere of rape, showed strongly antagonistic activity to a few of pathogenic fungus in vitro test. Bacillus subtilis TU100 was used as test material in this study and the fermentation conditions, antibiotic substance production of TU100 and the type of antibiotic substance along with its effect on Sclerotinia sclerotiorum were investigated.Optimum conditions for TU100 to produce antibiotic substance, the strain is eugonic and produces more antibiotic substance at 30°C.The initial optimum pH of liquid culture broth for bacteria and antibiotic substance production was 6-8. Sufficient oxygen and high carbon-nitrogen ratio of liquid culture broth enhanced the bacteria growth and antibiotic substance production. The growth of bacteria reached the highest level at 48h, otherwise, the maximum of antibiotic substance production come at 72h.The antibiotic substance was extracellular and secreted to culture medium. The sucstance had strong endurance to higher temperature and could keep its inhibiting activity in pH4-10. Adjusted the pH value of culture medium to 3 could make the substance deposited. The substance could dissolve in inorganic solvent such as water and organic solvent such as methanol, ethanol, etc. So the substance could purified ulteriorly by useing this deliquescent characteristic. Finally, by sephadex gel chromatogram the pure antibiotic substance could be obtained.Bacillus subtilis TU100 had a strong inhibiting activity against several pathogenic fungus,such as Sclerotinia sclerotiorum , Pseudocercosporella capsella(Ell.&Ev.)Deighton , Verticillium dahliae in cotton , Thanatephorus sasakii(Shirai)Ju, Watermelon Fusarium wilt,etc.When the antibiotic solution was diluted to 1000 times, it still kept its inhibiting activity.By inoculating TU100 on the leaf of rapeseed, soybean and cornin vitro test,TU100 could inhibite the growth of Sclerotinia sclerotiorum and B. maydis effectively.Inoculating Bacillus subtilis TU100 into rape plant through different methods could induce change of the activity of POD, PPO, PAL,accordingly make the plant produce resistance to plant diseases.