Genetic engineering modification to promote the synthesis of 1,2,4-butanetriol from cellulose hydrolysate of Escherichia coli
1,2,4-Butanetriol(BT)is one of the high value-added compounds widely used in various fields,and the production of BT by fermentation using cellulose hydrolysate requires a strain that can tolerate the inhibitors present in the hydrolysate.In the presence of furfural,a common inhibitor in hydrolysates,the fermentation of Escherichia coli is severely limited.In this study,four furfural tolerance genes,yghA,thyA,mdtJI,and pntAB were overexpressed in the BT-producing strain.In the presence of 0.4g/L furfural,all modified strains showed different degrees of growth.Among them,the strain overexpressing pntAB had the best growth,which also contributed to the enzymatic activity or transcriptional level of the enzymes in the BT pathway,yielding 11.0g/L BT.When corncob cellulose hydrolysate was used as the substrate,the strains overexpressing yghA,thyA,and pntAB all significantly improved the growth and BT production.The strain carrying yghA performed the best,yielding 3.36g/L BT in shake flasks and 15.3g/L BT in 5L fermenters,with a conversion of 63.8%.This strategy provided a reference for BT production by fermentation of corncob cellulose hydrolysate.
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