代谢工程改造大肠杆菌低pH环境下高效合成5-羟基戊酸OA

5-Hydroxyvaleric acid(5-HV)is an important five-carbon compound with a wide range of applications in the fields of pharmaceuticals,fragrances,and materials.At present,there are few studies on the biological production of 5-HV,which is mostly dis-covered as an intermediate and suffers from low yield and high production cost.In this study,a 5-HV-producing E.coli strain from our la-boratory was modified to synthesize 5-HV without induction by removing some elements of the lactose manipulator in the plasmid,thus avoiding the use of the costly and toxic inducer IPTG.The 5-HV titer was further improved by overexpressing the transcriptional activator of the rate-limiting enzyme aldehyde reductase,yqhC.To reduce the amount of base used during fermentation,the Hfq-DsrA antacid element was introduced into the chassis cells to improve the acid tolerance of the strain.Finally,in a 10 L fermenter,the pH of the fermentation broth was maintained in an acidic environment,and 47.5 g/L of 5-HV was achieved with a yield of 42％(glucose to 5-HV,mass frac-tion),while the amount of alkali added was reduced by 45％.The methodology and results of this study are instructive for the large-scale bioproduction of 5-HV.