Optimization of erythritol production by Candida magnoliae in fed-batch culture

A two-stage fed-batch process was designed to enhance erythritol productivi ty by the mutant strain of Candida magnoliae, The first stage (or growth st age) was performed in the fed-batch mode where the growth medium was fed wh en the pH of the culture broth dropped below 4.5, The second stage (or prod uction stage) was started with addition of glucose powder into the culture broth when the cell mass reached about 75 g dry cell weight l(-1), When the initial glucose concentration was adjusted to 400 g l(-1) in the productio n stage, 2.8 g l(-1) h(-1) of overall erythritol productivity and 41% of er ythritol conversion yield were achieved, which represented a fivefold incre ase in erythritol productivity compared with the simple batch fermentation process. A high glucose concentration in the production phase resulted in f ormation of organic acids including citrate and butyrate, An increase in di ssolved oxygen level caused formation of gluconic acid instead of citric ac id.