Abstract: Screening phenyllactic acid (PLA)-resistant strains enables effective reduction of the inhibitory effect of PLA on the synthesis process and thus an increase in PLA production. In this report, Escherichia coli BL21 (DE3) was mutagenized by UV irradiation and screened for a mutant resistant to PLA, E. coli Z2016 (CCTCC Accession No. M2016332). E. coli Z2016 was used the host strain to construct recombinant strains E. coli Z2016 pET-28a-ldhY52V and E. coli Z2016 pET-28a-ldhL for the synthesis of D- and L-PLA. The results showed that E. coli Z2016 was able to grow normally in a medium containing 1 g/L D-PLA. The production of D- and L-PLA by the recombinant strains were 6.75 and 6.97 g/(L·h), which were increased by 14.02% and 8.95% as compared to those produced by the original strain, respectively. During 120 min of fed-batch fermentation, the production of D-PLA by E. coli Z2016 pET-28a-ldhY52V was 20.02 g/L with a conversion rate of 90.97%, which was increased by 22.17% as compared to that produced by the control. The L-PLA concentration produced by E. coli Z2016 pET-28a-ldhL was 20.87 g/L, which was increased by 16.85% as compared to produced by the control, with a conversion rate of 91.24%. Accordingly, the use of PLA-resistant strains provided an effective method to increase PLA production.

Key words: UV mutagenesis, phenyllactic acid, phenyllactic acid-resistant strain, E. coli, whole-cell transformation