Study On The Optimal Culturel Conditions Of A Marine Bacteria Strain B-9987 (Bacillus Sp.) And The Chemical Properties Of Its Antifungal Substances

Isolated from sea water and sea mud in Donghai Sea, Bohai Sea, Zhujiang River and Huangdao Island , 4 strains of marine bacteria (B-9987, D-2682, H-9812, Q-9803) can strongly against the plant pathogenic fungi. The antifungi activity of B-9987 strain was the strongest among them. The culture conditions of B-9987 strain and antifungi activity were studied in present paperAt room temperature, the culture filtrate activity of B-9987 strain reduced little after 45d's storage. The activity was higher in alkaline condition but was more stable in acid situation. At pH=5.5, treated with high temperature and high pressure (120°C, 1 × 10~5 Pa, 20min), its activity was still remain 75%.Cultural conditions for B-9987 strain were also studied in this paper. The result showed that 2216E culture medium, pH5~9, 25~28°C, NaCl 0~4.5% were the acceptable ranges for both B-9987 strain growth and antifungal activity. The suitable conditions for activity were: improved 2216E culture medium, pH=7, 25°C, NaCl 1.5%, 84~120h, volume 50ml/250ml, rotative speed 150r/min. The optimum medium composition based on 2216E was determined by orthogonal design. When cultured with peptone 3‰, yeast l‰, NaCl 1.5%, glucose 3‰, the culture filtrate activity of B-9987 strain was the strongest.The antifungal substance of the B-9987 was purifified cursorily, and it was primarily considered as phenolic compounds. B-9987 antifungal substance is weak acid and is dissolvable in water , methanol, acetone,...