Effect of single- gene knockout of L- serine transport system on L- serine production in Escherichia coli

Transport system modification is an important method in strain improvement.It has been reported that the uptake of L- serine was regulated by four genes of sda C,cyc A,sst T and tdc C in Escherichia coli.In this study,the four single- gene knockout mutant strains of sda C,cyc A,sst T and tdc C were constructed,respectively. The fermentation results showed that the sda C and cyc A knockout mutants produced 16.3 g / L and 14.1 g / L L- serine,respectively,which were 43% and 25% higher than that of the control strain. However,the production of sst T and tdc C mutants were both similar to the control strain.