[Optimization of high-cell-density fermentation process for S-adenosyl-L-methionine production].

Poor stability existed in the anaphase of the high-cell-density fermentation of Saccharomyces crevisiae for S-adenosyl-L-methionine (SAM) production in 5 L fermentor. To improve the fermentation stability, we studied the addition of diammonium hydrogen phosphate, sodium glutamate and adenosine disodium triphosphate into glucose feeding solution. Study of four fed-batch cultures showed that, after 34 h fermentation, when dry cell weight reached 100 g/L, the addition of 50 g pre-L-methionine and glucose feeding with 10 g/L adenosine disodium triphosphate was optimal for SAM production. Under this condition, after 65.7 h fermentation, both the dry cell weight and the yield of SAM reached the maximum, 180 g/L and 17.1 g/L respectively.