S-Adenosyl-L-methionine production by Saccharomyces cerevisiae SAM 0801 using DL-methionine mixture: From laboratory to pilot scale

This study sought to develop a cost-effective biological catalysis process for S-adenosyl-L-methionine (SAM) production. During the process, a mixture of (D)-methionine ((D)-Met) and (L)-methionine (L-Met), namely (DL)-Met, was used as substrate to replace the conventional but expensive pure (L)-Met. The concentration of DL-Met in substrate was optimized. When 80 g/L of (DL)-Met was added in a 5 L-scale bioreactor, 13.74 g/L of SAM was produced with an (L)-Met conversion rate of 32.15%. The fermentation process was then scaled up to meet the requirements of realistic industrial SAM production. In a 300 L-scale fermentation process, 10.45 g/L of SAM was achieved, with an (L)-Met conversion rate of 32.61%. Moreover, the proportion of (D)-Met remaining in broth increased from 50% at the beginning to 76.89% at the end of fermentation. The fermentation process is generally appropriate for commercial SAM production.