Pilot- and plant-scale cultureIn a 300-l fermentor (KoBioTech), the first seed culture wasprepared in a 500-ml baffled flask in the same manner aspreviously described. For the second seed culture, the firstseed of 50 ml was inoculated to a 7-l jar containing 5 l ofseed medium. Then, the culture broth was cultivated for60 h at 30°C with 500 rpm and 1.0 vvm. The second seedof 10 l, obtained from two 7-l jar fermentors, was transferredto the 300-l fermentor containing 200 l of productionmedium and followed by cultivation for 120 h at 34°Cwith 260–480 rpm as the same velocity of the impeller tipto a 7-l fermentor and 1.0 vvm.In a 5,000-l fermentor (KoBioTech), the first and secondseed cultures were prepared in the same manner as describedpreviously. For the third seed culture, the secondseed of 5 l was added to a 300-l fermentor containing 100 lof seed medium. Then, the culture broth was cultivated for36 h at 30°C with 200 rpm and of 1.0 vvm. The third seedwas transferred to the 5,000-l fermentor containing 2,000 lof production medium and then cultivated for 120 h at 34°Cwith 130–240 rpm as the same velocity of the impeller tipto a 7-l fermentor and 1.0 vvm.Determination of impeller tip velocity as a scale-upparameterTo scale up from the laboratory scale (7-l jar fermentor) topilot (300 l) and plant (5,000 l) scales, the impeller tipvelocity (Vtip) was used as a scale-up parameter, and Vtipwas calculated by following equation (Wang and Cooney
1997): Vtip=2π N Di, where Vtip=impeller tip speed, N=
stirrer speed, and Di=impeller diameter. Diameters of
laboratory-, pilot-, and plant-scale impellors are 8, 15, and
30 cm, respectively.
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