Method for preparing alpha-ketobutyric acid by using L-threonine as substrate

The invention discloses a method for preparing alpha-ketobutyric acid by using L-threonine as a substrate, wherein a product, alpha-ketobutyric acid is prepared by using microbial complete cells containing synthetic L-threonine dehydratase as a biological catalyst, using the L-threonine as the substrate, and performing oscillating transformation at a rate of 50 to 250 turns/minute under the conditions that the temperature is between 20 and 65 DEG C and the pH is between 7.0 and 11.0. The method has the following characteristics that (1) a biological catalysis method is used, a reaction system is simple, reaction conditions are mild, steps are easy, and the operation is simple; and the biological catalyst can be easily removed, and the separation and purification of subsequent products are facilitated; (2) the transformation rate of the alpha-ketobutyric acid generated by the substrate, L-threonine can reach more than 99.6 percent, and the product, alpha-ketobutyric acid can be accumulated to reach a higher concentration; and (3) the substrate, L-threonine has a low price and is easy to obtain. According to the method, a basis of realizing high-efficient production of the alpha-ketobutyric acid is established.