Single-Cell Factory for Efficiently Synthesizing alpha-aminobutyric Acid and Construction and Application thereof

摘要

The present invention discloses a single-cell factory for efficiently synthesizing α-aminobutyric acid and construction and application thereof, which belong to the technical field of microorganisms. The present invention expresses an L-threonine deaminase gene, an L-amino acid dehydrogenase gene and a dehydrogenase gene for providing cofactor NADH cycle in tandem to construct a recombinant Escherichia coli single-cell factory which is used for efficiently synthesizing α-aminobutyric acid. The expression level of the L-threonine deaminase is optimized and controlled by an RBS sequence, so that the problem of transformation inhibition caused by the rapid accumulation of an intermediate product ketobutyric acid is solved, moreover, the expression level of the dehydrogenase for providing cofactor NADH cycle is optimized and controlled by a promoter and an RBS sequence, consequently, the NADH regeneration rate is increased, and ultimately, yield is increased. Utilizing the single-cell factory to carry out whole-cell transformation can reduce obstacles to substances getting in and out, increase the transformation rate and promote the intracellular cycle of cofactors without requiring exogenous addition, and the cost is low. Within 20 h, the yield of the recombinant Escherichia coli single-cell factory in a 5 L fermentation tank is 204 g·L⁻¹, the space-time yield is 10.2 g·L⁻¹·h⁻¹, and a practical effective strategy is provided for industrialized production