The invention discloses a method for preparing L-
tertiary leucine based on biological
brick tandem double enzymes. The method comprises the following steps: (1) constructing a tandem biological
brick element capable of realizing tandem expression of
leucine dehydrogenase and
formate dehydrogenase; (2) introducing the tandem biological
brick element into
Escherichia coli (E.coli) so as to construct E.coli
engineering bacteria based on tandem expression of
leucine dehydrogenase and
formate dehydrogenase; (3) inoculating the E.coli
engineering bacteria into a liquid enlarged culture medium containing chloromycetin for carrying out culture and induced expression to obtain
fermentation liquid, carrying out refrigerated
centrifugation to obtain cells, and re-suspending and washing with a
buffer solution so as to obtain
cell sap; and (4) putting the
cell sap, trimethylpyruvic acid, amino donors, coenzymes and cosubstrates for regeneration of the coenzymes in a buffer
system for carrying out vibration reaction, and carrying out whole-
cell catalysis asymmetric
reductive amination to obtain the product, namely L-
tertiary leucine. The method disclosed by the invention has the advantages that the product conversion rate is high, the
chiral selectivity is better, the
reaction conditions are mild, the operation is simple, the expensive coenzymes can be regenerated, and the cost is saved by expressing the double enzymes with single cells.