Patent ID: 8252579

Claim:
A method for the preparation of a strain of evolved E. coli for the production of 1,2-propanediol by the metabolism of a simple carbon source, said method comprising: (a) providing an initial E. coli strain comprising deletion of tpiA gene and deletion of at least one gene involved in the conversion of methylglyoxal (propanal) into lactate; (b) culturing the initial E. coli strain, under selection pressure in an appropriate growth medium comprising a simple carbon source for a time period sufficient to allow an increase in growth; (c) causing evolution, in said E. coli strain, of one or more genes involved in the biosynthesis pathway from DHAP to methylglyoxal and then to 1,2-propanediol towards evolved genes having an improved 1,2-propanediol synthase activity by applying increasing rates of dilution in such a way as to conserve in the growth medium only those E. coli strain that display a growth rate equal to or higher than the imposed rate of dilution, to provide an evolved strain; and (d) selecting and isolating the evolved E. coli strain having an improved 1,2-propanediol synthase activity, wherein the initial E. coli strain comprises deletion of genes gloA, aldA, and aldB.