1. Fed-batch fermentation
Fed-batch experiments were performed with glucose maintained at around 5 g/L to determine the growth characteristics of YL-C11 (Figure 1). Cell growth increased rapidly during the 12-42th h fermentation. After 42 h fermentation, cell growth entered the stationary period. Although cell growth was in a stationary phase, the synthesis of β-carotene continued. It was not until the 96th h of fermentation that the synthesis of the β-carotene trend finally stopped. Glucose (1200 g) was consumed during fermentation. The DO value decreased rapidly in the first 28 h of fermentation and reached 0% when the fermentation time extended from 28 to 120 h. Cell biomass reached 73.5g, and β-carotene concentration reached 0.3g/L at the end of fermentation. The results showed that the biomass and β-carotene concentration were at a low level, and there is potential for improvement.