Studies On The Fermentation Condition Of Streptomyces Roseoflavus Men-myco-93-63

Streptomyces is a kind of Gram-positive bacteria which exist in the soil. They are a kind of important microorganisms used in industrial production. Microorganisms in this genus can produce kinds many bioactive compounds. Streptomyces roseoflavus Men-myco-93-63 is a strain isolated from soil and showed strong inhibition against Verticillium dahliae. In this research, Verticillium dahliae was used as the target pathogen to study the substrate and culturing conditions for achieving higher productivity.Study for substrate was carried out for optimizing nutritional requirements. First the concentration of glucose was tested. Then different carbon sources (starch, dextrin, sucrose, maltose) were tested as a combination with glucose. Various of nitrogen sources (peanut meal, corn slurry, yeast extract, beef extract, urea, peptone, (NH₄)₂SO₄, NH₄NO₃, NaNO₃) was studied. Similarly, optimum requirements for micronutrients were also studied by varying the concentration of FeSO₄, ZnSO₄, MgSO₄, MnCl₂, CoCl₂, KH₂PO₄, CaCO₃, NaCl. Some factors were chosen. In the last, the chosen factors were optimized by orthogonal design. The optimized fermentation medium consisted of 2.4% glucose, 0.8% starch, 0.8% corn slurry, 1.5% peanut meal, 0.4% NaCl, 0.02% KH₂PO₄,0.3% CaCO₃. Its cost reduced 76% and inhibition zone enhanced 27% compared to former medium.In optimizing seed medium, the concentration of carbon and nitrogen sources was changed in another orthogonal design. In this experiment, biomass was chosen as the index and seed substrate was got. Its components were: 1.8% glucose, 1.4% corn slurry, 0.5% peanut meal, 0.4% NaCl, 0.02% KH₂PO₄, 0.3% CaCO₃.Some fermentation control parameters including aeration, agitation, pH, temperature of incubation, fermentation cycle time, etc were studied. The germ culturing condition was as follows: the inoculums was grown in 50 ml seed medium in 500 ml Erlenmeyer flasks at 30℃ for 30 h on a rotary shaker (220 r/min). Of this, 8% v/v seed was transferred to 100 ml production medium in 500 ml Erlenmeyerflasks. Fermentation was carried out at 30°C for 140 h. Metabolizing curve was tested in Erlenmeyer flasks.After optimizing nutritional requirements and control parameters at shake flask level, scale up studies were carried out in 30 L fermentor. The metabolizing parameters including pH, biomass, total sugar, deoxidize sugar, ammonia nitrogen and output were tested. It laid a foundation for large scale fermentation.