Deletion of d-ribulose-5-phosphate 3-epimerase (RPE1) induces simultaneous utilization of xylose and glucose in xylose-utilizing Saccharomyces cerevisiae

Abstract

Simultaneous co-utilization of xylose and glucose is a key issue in engineering microbes for cellulosic ethanol production. We coupled xylose utilization with glucose metabolism by deletion of D-ribulose-5-phosphate 3-epimerase (RPE1) through pentose phosphate pathway flux. Simultaneous utilization of xylose and glucose then occurred in the engineered Saccharomyces cerevisiae strain with the xylose utilization pathway. Xylose consumption occurred at the beginning of glucose consumption by the engineered yeast without RPE1 in a mixed sugar fermentation. About 3.2 g xylose l(-1) was utilized simultaneously with consumption of 40.2 g glucose l(-1) under O2-limited conditions. In addition, an approximate ratio (~1:10) for xylose and glucose consumption was observed in the fermentation with different sugar concentration by the engineered strain without RPE1. Simultaneous utilization of xylose is realized by the coupling of glucose metabolism and xylose utilization through RPE1 deletion in xylose-utilizing S. cerevisiae.

Enhancement of Simultaneous Xylose and Glucose Utilization by Regulating ZWF1 and PGI1 in Saccharomyces Cerevisiae

“…In the strain SyBE_Sc17004, xylose metabolism was coupled with the metabolic flux of glucose into the PP pathway by RPE1 deletion [5]. G6PDH is the key enzyme to control the metabolic flux in the PP pathway from glucose.…”

“…In our previous research, RPE1 deletion achieved simultaneous glucose and xylose utilization by coupling glycolysis and PP pathway in the strain SyBE_Sc17004 [5]. Xylose utilization was closely related with the metabolic flux of glucose into the PP pathway.…”

“…Transporter engineering for xylose significantly improved xylose utilization by increasing the affinity of the transporter for xylose [5]. If the transporter is the limiting step for xylose utilization in present biosystems, sugar concentration and the ratio of xylose and glucose would influence xylose utilization significantly.…”

“…Efficient xylose utilization in the lignocellulosic hydrolysate is an important issue for economic bioconversion of lignocelluloses [4][5][6][7]. To achieve high product titer, solid-tosolid pretreatments have been preferred to facilitate fermentation with high solid loading of feedstock [8][9][10].…”

“…Except for transporter engineering, reconstitution of carbohydrate metabolic networks, such as the phosphoketolase pathway, is another approach to improve xylose utilization [15,28]. Recently, it has been reported that disruption of some genes in glycolysis and pentose phosphate (PP) pathway resulted in simultaneous xylose and glucose utilization [5,29]. Although simultaneous xylose and glucose utilization has been achieved in several studies, sugar consumption rate needs to be improved.…”