Aspartase reactor system

Using a column packed with immobilized E. CoZZ cells, conditions for continuous production of L-aspartlc acid from ammonium fumarate were investigated in detail, and an aspartase reactor system was designed. The system is essentially the same as that for the immobilized amlnoacylase system [2]. A solution of 1 M ammonium fumarate (containing 1 mM MgClz, pH 8.5) is passed... 

The substrate, L-aspartate, is produced from fumarate by an enzyme system involving aspartase, as described in the section on L-aspartate. To produce L-alanine directly from fumarate, the L-alanine-producing column was connected in tandem to an L-aspartate-producing column. In this tandem column system, side reactions caused by fumarase in Escherichia coli and alanine racemase in P. dacunhae reduced the yield. Then, both bacterial cells were separately treated with high temperature and low pH, respectively, and the enzymes responsible for the side reactions were inactivated. Immobilization of these two kinds of bacterial cells with K-carrageenan resulted in the production of L-alanine in a single reactor without the production of the side products, malate and o-alanine (Takamatsu et al. 1982 Chibata et al. 1986b). 

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