Isolation Of High-Producers Of S-Adenosylmethionine And Optimization Of Fermentation Process

S-adenosylmethionine (SAM) is an important physiological active substance that participates in more than 40 kinds of biochemical reactions in vivo. In the pathological state, S-adenosylmethionine must be activated to replace L-methionine (L-Met) as nutrients to support normal metabolism. Be controlled by high performance liquid chromatography (HPLC), a simple and practical determination by UV-visible spectrophotometry was determined in this study. High-yield strains of S-adenosylmethionine were isolated from 45 strains of yeast. The fermentation process was optimized also in this page. Main contents and the results are as follows:(1) A determination by UV-visible spectrophotometry of S-adenosylmethionine contents of fermentation broth was established. Using HPLC as a reference, a simple and convenient determination of S-adenosylmethionine contents was established after removal of nucleic acid of fermentation broth. Results of UV detection of S-adenosylmethionine contents were compared to HPLC. Two testing methods had a high correlation. The regression polynomial equation between them was:y=-0.2676x4+ 1.3309x3-2.377x2+2.4362x+0.2094, R2=0.9125. There was a good linear relationship between S-adenosylmethionine contents detected by ultraviolet spectrophotometry absorbance and HPLC in the range of 0.006 g/L-0.30 g/L. The working curve of UV was: y2=36.886x+0.0106, R2=0.9996. Recovery was 92-98%. Relative error was 1.10%; Relative standard deviation was 1.33%. UV detection had good stability at 30 min; UV detection also had high precision, accuracy, and high sensitivity. The UV deremination could be used in high-volume testing on isolation of higher producer of S-adenosylmethionine.(2) Higher producers were isolated from45 strains of yeasts that can be classified into 11 genuses. There were significantly differences of S-adenosylmethionine contents among different genus of yeast. The contents of S-adenosylmethionine were between 0.01 g/L and 2.05 g/L. S-adenosylmethionine contents of Saccharomyces were significantly different from other genus of 45 strains. Two high-yield S-adenosylmethionine stains both were Saccharomyces cerevisiae (A 12A, A18A) which S-adenosylmethionine were 2.05 g/L and 1.90 g/L respectively.(3) Using the two high-yields S-adenosylmethionine stains that both were Saccharomyces cerevisiae (A12A, A18A) as the object, the effects of fermentation conditions on the cell dry weights and S-adenosylmethionine contents were studied, and the fermentation conditions were optimized in this study. There were significant effects (P<0.05) of fermentation temperature and initial fermentation pH, rotation speed and fermentation time on the cell dry weight and S-adenosylmethionine production. After the orthogonal optimization, the most suitable conditions for SAM accumulation were: temperature 25℃, initial pH 6.0, shaking speed 225 r/min, and feeding time 108 h. In this fermentation conditions, the SAM production of Saccharomyces cerevisiae A18A was up to 2.54 g/L broth,which was 1.17-fold higher than before.