3.2 High-density fermentation in a 5-L fermenter
A scale-up fermentation was carried out in a 5-L fermenter, and samples were collected every 6 h to analyze OD600, total protein concentration, and enzyme activity. The whole process of high-density fermentation lasted for 108 h. As is showed in Fig. 2, in the fed-batch with glycerol as carbon source, OD600 increased continuously, reaching the highest value of 716±15 at 102 h, and then decreased, which may be due to the fact that the dissolved oxygen can not maintain the growth of such high density cells under the experimental conditions. In the 102-h sample, the total protein concentration and AGL activity in the culture supernatant were as high as 0.732 mg/mL and 9.11 U/mL, respectively, which exhibited the same growth trend as cell mass.
Figure 2