Recombinant strains of Escherichia coli for L-aspartic acid biosynthesis

The aspartase overproducing mutant B-715 was used as a donor of the aspartase gene for further construction of the aspartase-hyperproducing strains by molecular cloning. In preliminary experiments activity of transformants and their efficiency in L-aspartic acid biosynthesis were compared. The conditions for recombinant strain multiplication, biomass activation and L-aspartic acid biosynthesis were optimized. The optimum temperature for cells multiplication, their activation and for product biosynthesis was 37 degrees C. Two-stage process of the multiplication of bacteria (first in LB medium, and then in FF medium) eliminates the appearing of the inclusion bodies of aspartase in the cells. The shaking during cell activation improved cells productivity. The change of pH in the course of the biosynthesis process was insignificant but did not influence the process.