苯基乳酸耐受性大肠杆菌的筛选及其高产苯基乳酸特性

苯基乳酸(phenyllactic acid,PLA)耐受性菌株的筛选能够有效降低PLA对生产菌株的抑制作用,有利于PLA产量的提高。通过紫外诱变的方法筛选耐受PLA的菌株,并应用于PLA的合成。以Escherichia coli BL21(DE3)作为原始出发菌株,通过紫外诱变的方法诱变筛选获得一株耐受PLA突变菌株E.coli Z2016(CCTCC保藏编号M2016332)。以E.coli Z2016为宿主菌,分别构建了重组菌株E.coli Z2016 pET-28a-ldh~(Y52V)和E.coli Z2016 pET-28a-ldhL用于D-和L-苯基乳酸的合成。结果表明:E.coli Z2016在含有1 g/L D-PLA的培养基中能够正常生长;重组突变菌株E.coli Z2016 pET-28a-ldh~(Y52V)和E.coli Z2016 pET-28a-ldhL全细胞合成D-PLA和L-PLA产量分别为6.75、6.97 g/(L·h),较重组出发菌株分别提高了14.02%和8.95%;分批补加底物反应120 min,E.coli Z2016 pET-28aldh~(Y52V)得到的D-PLA为20.02 g/L,较对照组提高22.17%,转化率为90.07%;E.coli Z2016 pET-28a-ldhL得到的L-PLA产量为20.87 g/L,较对照组提高16.85%,最终转化率为91.24%。筛选耐受性菌株是提高PLA产量的有效途径。

Screening of Phenyllactic Acid-Resistant Escherichia coli and Its Application in the Synthesis of Phenyllactic Acid

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.