Construction And High-rate Expression Of GlyA Recombinant Bacteria

L-Serine is used as a component of amino acids mfusion,an additive of cosmetics,and as a starting material for the enzymatic production of tryptophan. The fermentative production of L-serine directly from carbohydrates has not been established because the metaboic turnover of this amino acid is much quicker than that of other amino acids: L-serine is a key intermediate for the synthesis of several other amino acids, nucleic acids and phospholipids. Because of its advantages of cheao raw material, available raw material and high concentration of L-serine in the reaction solution,the enzymatic method becomes the most promising one for manufacturing L-serine.With the chromosome DNA of Escherichia coli K12 and Pseudomonas aeruginosaT46 as templates, PCR products containing glyA gene encoding SHMT was obtained with the length of about 1.3kb. The PCR products were insertsed into pETblue .Then the two recombinant plasmids were transformed into E.coliTuner (DE3)placI. Among the transformants, recombinant bacteria over-expressing SHMT were screened out. Then the conditions for converse enzymatic reaction were optimized.