Simultaneous utilization of glucose and mannose from woody hydrolysate for free fatty acid production by metabolically engineered Escherichia coli

In this study, the Escherichia coli strain MG1655 with fadD mutant (named as ML103), and MG1655 with fadD and ptsG double mutant (named as ML190) carrying the plasmid with the acyl-ACP thioesterase (TE) from Ricinus communis (pXZ18) or the plasmid with the combination of the TE and the native (3R)-hydroxyacyl-ACP dehydrase (fabZ) (pXZ18Z), produced free fatty acids (FFAs) efficiently using mannose as the sole carbon source. Due to the carbon catabolite repression (CCR) regulation, ML103(pXZ18) utilized glucose and mannose sequentially in the mixed sugar culture, while ML190(pXZ18) and ML190(pXZ18Z), with ptsG mutation, used glucose and mannose simultaneously. The highest total FFA concentration from the mixed sugar culture reached 2.96 g/L by ML190(pXZ18Z). Furthermore, the strain ML190(pXZ18Z) can produce 2.86 g/L FFAs with a high yield of 0.23 g/g using hydrolysate mainly contained glucose and mannose from a commercial plant.