Enhancement of furan aldehydes conversion inZymomonas mobilisby elevating dehydrogenase activity and cofactor regeneration.
BACKGROUND
Furfural and 5-hydroxymethylfurfural (HMF) are the two major furan aldehyde inhibitors generated from lignocellulose dilute acid pretreatment which significantly inhibit subsequent microbial cell growth and ethanol fermentation.Zymomonas mobilisis an important strain for cellulosic ethanol fermentation but can be severely inhibited by furfural and (or) HMF. Previous study showed thatZ. mobiliscontains its native oxidoreductases to catalyze the conversion of furfural and HMF, but the corresponding genes have not been identified.


RESULTS
This study identified a NADPH-dependent alcohol dehydrogenase gene ZMO1771 fromZ. mobilisZM4, which is responsible for the efficient reduction of furfural and HMF. Over-expression of ZMO1771 inZ. mobilissignificantly increased the conversion rate to both furfural and HMF and resulted in an accelerated cell growth and improved ethanol productivity in corn stover hydrolysate. Further, the ethanol fermentation performance was enhanced again by co-expression of the transhydrogenase geneudhAwith ZMO1771 by elevating the NADPH availability.


CONCLUSIONS
A genetically modifiedZ. mobilisby co-expressing alcohol dehydrogenase gene ZMO1771 with transhydrogenase geneudhAshowed enhanced conversion rate of furfural and HMF and accelerated ethanol fermentability from lignocellulosic hydrolysate. The results presented in this study provide an important method on constructing robust strains for efficient ethanol fermentation from lignocellulose feedstock.
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China.
Xia
X
Wang
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China.
Qiuqiang
Q
Gao
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China.
Jie
0000-0001-6521-3099
J
Bao
5-Hydroxymethylfurfural (HMF); Alcohol dehydrogenase; Furfural; Reduction; Transhydrogenase; Zymomonas mobilis