The optimized Toyocamycin production medium contained the following in kg/m3: Corn Starch or 60K Dextrin 30, Glucose 10, NaCl 10, Nutrisoy 20, OM Peptone 20, BND Peptone 10, MgCl2 9.95, Dow Corning P2000 Antifoam 0.1% v/v, Soy Oil 1% v/v, pH controlled by addition of NaOH or H2SO
Other groups had previously reported that TM could be produced by Streptomyces rimosus at temperatures up to 36 oC. An increase in final TM titer on QTM was observed using Streptomyces crestomyceticus with increasing incubation temperature from 28 oC to 40 oC (Fig. 11). A maximum QTM of 65 ug/cm3 . h was calculated from the data obtained at 36 oC with decreasing rate above this temperature.
Oxygen uptake rates and CO2 evolution rates (determined from exhaust gas analysis) were rapid during the initial 20 h following inoculation Fig. 12, 13). The respiratory quotient remained between 0.8 and 1.3 throughout 150 h fermentations of either the parent FCRF 341 or mutant U190.
After the initial 50 h of incubation, neither high dissolved oxygen tensions of 20-80% of air saturation (Fig.12) nor low dissolved oxygen tensions of 0-40% of air saturation (Fig. 13) appeared to affect TM titer or specific productivity. Neither oxygen transfer rate (OTR) nor dissolved tension correlated with TM titer or productivity. This was confirmed by numerous 120 dm3 batch fermentations.
The addition of 1% soy oil increased the ratio of TM produced per mole CO2 evolved at constant pH, but did not appear to stimulate total oxygen uptake or total CO2 evolved. Total carbohydrate uptake from either the starch 5S or dextrin 5D medium was not affected by dissolved oxygen tension, at pH between 6.0-6.5. However, the yield (in grams of antibiotic produced per gram of starch consumed) increased from 5-6 g TM . g-1 carbohydrate to 7-10 g TM . g-1 with the addition of 1% soy oil to the medium (86, 87).
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