Fermentation in Shake Flask for Producing Antifungal Metabolite by Streptomyces Strain III-61

A study on the fermentation process in shake flask to produce antifungal active substance by Streptomyces Ⅲ-61,a biocontrol strain isolated from the forest soil in a suburb of Beijing,was launched.The fermentation medium was optimized by orthogonal experiment.The result showed that the optimal liquid medium was composed of 1.5% soybean meal,0.3% peptone,1.0% sucrose,1.3% soluble starch,0.02% KH2PO4,0.025% MgSO4·7H2O and 0.5% NaCl.The initial pH of the solution was adjusted to 7.0—7.4,then 1% CaCO3 was added.The culture conditions were screened with mono-factor test,and the most suitable technical parameters were summed up as follows:the liquid seed was cultured for 24 hours,the fermentation was carried out in 500mL erlenmeyer flask with 80mL production medium inoculated with 5%—10% seed culture and incubated at 240 r/min,31℃ for 96—120 hours.The inhibition zone diameter against Botrytis cinerea up to 49.5mm by the germfree filtrate from fermented broth of strain Ⅲ-61 obtained with the optimized fermentation process,which is 45.59% higher than that produced by the basic medium and initial fermentation process.