Preliminary Studies On The 024-Strain Of Actimycetes And Its Antibiotic

This paper studied the screening and identification of a new Actinomycetes ( 024 ) for controling the disease caused by Rhizoclonici cerealis on wheat, its initial and optimal fermentation condition of production of antifungal substance, and the methods of purification, the physical and chemical character.etc..The actinomyces was idicntified as a new species of the Microsircplosporu Its antifungal spectrum 024-antibiotic includes many plantpathogenic fungi, such as Glomerella cingulata, Fusarium gramiaearum, Helmmthosporiuin sativitnt, /iotrvosphticriu dothidea, Alternaria xolani, Endothia parasitica etc..The results show that the composition of initial fermentation medium is soybean cake 10g/L, glucose 10g/L, peptone3g/L, NaCl 2.5g/I,, CaCO3 2g/L, The condition is the initial pH of medium 7.0, 50ml liquid medium in 250ml flask, fermentation temperature 28℃. HOrpm for 10days; the composition of optimal fermentation medium is soybean cake 10g/L, glucose 10g/L, peptone.1g/L. NaCl 2.5g/L, CaCO3 2g/L, MgSO4 5mmol/L, KH2PO4 5mmol/L, FeCl3 1mmol/L. The optimal condition is the initial pH of medium 7.0, 50ml liquid medium in 250ml flask, fermentation temperature 28℃ -39℃(changing the temperature at 24th h), 1 70rpm for 2days. After the initial medium was improved, the activity of 024-antibiotic was increased obviously ( 79.2% ), the colour of fermentation broth was changed from henna into buff and the filter rate was speeded. Through investigating the character of the fermentation broth, the following conclusions can be drawn that the antifungal substance is thermostable and not protein: it has better control effect against wheat sharp eye-spot under mid-concentrationjiowever decrease the effect under high- concentration ; the molecular weight is bigger; it can improve the wheat seed germination rate and promote its growth.Different extracting and purifing methods were taken, such as organic solvent extraction, soak, alumina column chromatography and silica gel column chromatography etc.. At last, the effective approach was found that the 024-antibiotic can be purified by freez-dry, methyl alcohol soaking, acetone, chloroform, and methyl alcohol continuously washing, alumina and silica gel column chromatography.The 024-antibiotic is achromatic, diffluent in water, and can be dissolved in methyl alcohol and ethanol.it is difficult for 024-antibiotic to be dissolved in acetone, chloroform, n-butanol, acetic anhydride and benzene. It is stable in organic solvent. In the range pH6-8, the 024-antibiotic has strong inhibilitory activity, and out of the range the activity will drop rapidly.lt can be absorbed at 234nm tempestuously.