Construction method for escherichia coli Ecoli-SL26 knocked out by purine nucleoside phosphorylase gene

The invention discloses a construction method for escherichia coli Ecoli-SL26 knocked out by purine nucleoside phosphorylase gene. In the method, with the adoption of the homologous recombination knockout purine nucleoside phosphorylase gene of Red/ET system, the strain Ecoli-SL26 which is successfully knocked out by the purine nucleoside phosphorylase gene is selected under the double resistance of tetracycline (Tet) and kanamycin (Kam). Via the method disclosed by the invention, a route of hydrolyzing inosine into hypoxanthine is successfully provided, the conversion rate of enzymatic catalysis and the purity of 5'-phosphorylated inosine are increased, the loss and the production cost of inosine are reduced, and subsequent extraction for 5'-phosphorylated inosine and application for residual inosine are promoted. The method disclosed by the invention has important significance for the industrialization process of enzymatic catalysis for inosine 5'-phosphorylation.