Development of an Escherichia coli whole cell biocatalyst for the production of L-amino acids.

A whole cell biocatalyst for the enzymatic production of L-amino acids from hydantoins was created by coexpressing the genes encoding the L-hydantoinase, the L-N-carbamoylase and the hydantoin racemase from Arthrobacter aurescens in Escherichia coli. In order to construct a well balanced reaction system the enzymatic activity in the cells was varied by using vectors with different copy numbers for expression of the genes. Derivatives of pSC101, pACYC184 and pBR322 were employed for the various constructions and in one construct the hydantoinase gene was integrated into the E. coli chromosome. All constructs carried the E. coli rhamnose promoter system enabling gene expression control by transcriptional regulation. The productivity for L-tryptophan from the corresponding hydantoin was more than 6-fold higher than achieved with Arthrobacter aurescens.