Optimization of culture conditions for erythritol production by Torula sp..
Kyoung-Ah Kim, Bong-Soo Noh, Jung-Kul Lee, Sang-Yong Kim, Yong-Cheol Park and Deok-Kun Oh*
Journal of Microbiology and Biotechnology 10(1): 69-74. 2000.02.28.
(SCI I/F: 1.381)
The medium for erythritol production by Torula sp. in a 500-ml baffled flask was optimized to be 300 g/l sucrose, 10 g/l yeast extract, 3 g/l KH2PO4, and 10 mg/l CuSO4. 5H2O at 34C with initial pH of 5.5. Using this optimal medium, erythritol of 166 g/l was obtained after 140 h of cultivation, corresponding to 55.3% of the erythritol yield from sucrose with a productivity of 1.11 g/l/h. Optimal concentrations of carbon and nitrogen sources in a fermentor were higher than that in a flask due to the higher oxygen supply of the fermentor. Employing the medium containing 300 g/l or 400 g/l sucrose for the determination of optimal C/ N ratio, the C/N ratio was found to be more important than the nitrogen concentration for effective erythritol production. The optimal ratio of yeast extract to sucrose (g/g) was 20. The yield and productivity of erythritol were maximal in the medium containing 400 g/l sucrose and 20 g/l yeast extract. When dissolved oxygen in the culture was increased, the cell mass increased but the erythritol production was maximal in the range of 5 to 10% of dissolved oxygen. Under the optimal culture condition of the fermentor, a final erythritol concentration of 200 g/l was obtained after 120 h with a yield of 50% and the productivity was 1.67 g/l/h. The yield was the highest among erythritol-producing microorganisms.
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