Study On Screening, Isolating And Purifing Of The Antagonistic Substances Of A Biocontrol Agent SF1Against Fusarium Oxysporum F.Sp.Lini

We made a systemic study on a biocontrol agent which was isolated from pathogenic soil of linseed. The antagonistic activity in vitro had been tested and the antagonistic substances were screened, isolated and purified. The main contents and results were as follows:1. By using duel culture technique, we tested the antagonistic activity of strain SF1against Fusarium oxysporum f. sp. lini in vitro. The result showed that the inhibiting rate of fermentation broth of SF1could be58.99±0.01%.2. Besides morphological, physiological and biochemical characteristics, we used sequencing of16S rDNA and partial gyrA gene to identification of strain SF1.We found that SF1belonged to Bacillus atrophaeus, which could been used in biocontrol.3.The effect of different seed age, fermentation time, different temperature and pH on antagonism had been studied. The results showed that the optimum fermentation conditions were confirmed:seed age8h, fermentation time24h.The fermentation broth could been store at4-44℃.The best pH of buffer solution used in purification was7.0-11.0.4.The antagonistic substances were from exocytosis and they were volatile substances and proteins. Activated carbon had been used to collected the volatile substances and GC-MS was chosen to finish their analysis. The results showed that there were about24kinds of volatile substances, such as propionic acid, butyric acid, phenol, et al. Proteins was purified using ammonium sulfate precipitation and gel filtration chromatography. We gained two parts,G75-1and G75-2.The inhibitive activity were323.42%/mg and168.18%/mg respectively.0.92%of G75-1was recovered with26.65-flod purification, while0.76%of G75-2was recovered with13.86-flod purification. Their molecular weights were tested by SDS-PAGE. G75-1was about40.5KDa, and G75-2was about19.5KDa.