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Screening of L-Serine Producer and the Fermentation Conditions in Shake-Flask Culture

About 130 microorganisms isolated from soil on the minimal medium containing 50 mL/L methanol and 5 g/L glycine were examined for L-serine accumulation. Strain A3, a bacterium, was identified as Micrococcaceae. The strain produced 1.4 g/L L-serine when glycine was added in the growth medium. The cultural conditions of converting glycine to L-serine were investigated, including initial methanol and glycine concentration, carbon sources, nitrogen sources, initial pH of medium and time course of L-serine production. The results showed that the strain A3 could produce L-serine in shake culture at 31 ℃ in the medium containing glycine, the sole carbon source. The high concentration of glycine was necessary for L-serine accumulation during the fermentation. The addition of glucose, glycerol, etc. In the glycine containing medium was beneicial to the cell growth but not favorable for the production of L-serine.