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. 2017 Mar 6:7:43875.
doi: 10.1038/srep43875.

Engineered yeast with a CO2-fixation pathway to improve the bio-ethanol production from xylose-mixed sugars

Yun-Jie Li  1   2   3 , Miao-Miao Wang  1   2   3 , Ya-Wei Chen  1   2   3 , Meng Wang  1   2   3 , Li-Hai Fan  1   2   3 , Tian-Wei Tan  1   2   3
Affiliations

Engineered yeast with a CO2-fixation pathway to improve the bio-ethanol production from xylose-mixed sugars

Yun-Jie Li et al. Sci Rep. .

Abstract

Bio-ethanol production from lignocellulosic raw materials could serve as a sustainable potential for improving the supply of liquid fuels in face of the food-to-fuel competition and the growing energy demand. Xylose is the second abundant sugar of lignocelluloses hydrolysates, but its commercial-scale conversion to ethanol by fermentation is challenged by incomplete and inefficient utilization of xylose. Here, we use a coupled strategy of simultaneous maltose utilization and in-situ carbon dioxide (CO2) fixation to achieve efficient xylose fermentation by the engineered Saccharomyces cerevisiae. Our results showed that the introduction of CO2 as electron acceptor for nicotinamide adenine dinucleotide (NADH) oxidation increased the total ethanol productivity and yield at the expense of simultaneous maltose and xylose utilization. Our achievements present an innovative strategy using CO2 to drive and redistribute the central pathways of xylose to desirable products and demonstrate a possible breakthrough in product yield of sugars.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. Engineered S. cerevisiae for co-utilization of xylose, maltose and CO2.
MAL: maltose transporter; HXT: hexose transporter; XR: xylose reductase; mXR: xylose reductase with the mutant of R276H; XDH: xylitol dehydrogenase; XK: xylulokinase; PRK: phosphoribulokinase; Rubisco: ribulose bisphosphate carboxylase-oxygenase; PPP: pentose phosphate pathway; G6PDH: glucose 6-phosphate dehydrogenase; PGD: 6-phosphogluconate dehydrogenase; PDC: pyruvate decarboxylase; P: phosphate; BP-bisphosphate; ATP: adenosine triphosphate.
Figure 2
Figure 2. Fermentation profiles of YSC000, YSC110 and YSC111 in YP medium containing 70 g/L glucose with IA (IA+) or without IA (IA-) addition.
Figure 3
Figure 3. Fermentation profiles of YSX4C000, YSX4C110, YSX4C111 and YSX4C222 in YP medium containing 30 g/L maltose and 30 g/L xylose.
Figure 4
Figure 4
Intracellular 13C-G3P contents (a) and MFIh-CO2 values (b) of YSX4C000, YSX4C111 and YSX4C222.
See this image and copyright information in PMC

References

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