Abstract: The liquid fermentation medium and culture conditions to produce antibacterial substances capable of inhibiting Fusarium graminearum as a plant pathogenic fungus were studied. The anti-Fusarium graminearum activity of fermentation broth was measured by agarose diffusion method. The optimal fermentation medium was determined to consist of 1 g/100 mL soybean meal, 1.5 g/100 mL corn flour, 1g/100mL wheat bran, 0.5 g/100 mL rice flour, 0.07 g/100 mL KH2PO4, 0.03 g/100 mL MgSO4, 0.1% CaCO3, and sea water (natural pH). The optimal fermentation conditions were as follows: the medium pH was adjusted to pH 9.0 and the filled volume was 110 mL in a 500 mL shake flask at a shake speed of 180 r/min; the inoculum was inoculated at a level of 7% for a fermentation duration of 33 h at 28 ℃. The resulting fermentation broth had strong antibacterial effects on 16 selected plant pathogenic fungi with an inhibitory bandwidth exceeding 7 mm, and also showed inhibitory effects on 5 tested bacteria.

Key words: marine Paenibacillus polymyxa L1-9, antimicrobial substances, fermentation conditions, inhibition spectrum