Construction of Recombinant with Ethanol and Aldehydes Tolerance via Overexpression of Aldehyde Reductase.

Furfural and hydroxy-methyl-furfural (HMF) are produced by lignocellulosic biomass during heat or acid pretreatment and are toxic to yeast. Aldehyde reductase is the main enzyme to reduce furfural and HMF. To improve the conversion efficiency of lignocellulosic biomass into ethanol, we constructed with overexpression of aldehyde reductase (encoded by ). The gene of aldehyde reductase (encoded by ) was cloned via polymerase chain reaction (PCR) and ligated with the expression vector pGAPZαC. Western blot coupled with anti-His tag confirmed overexpression of the gene. The growth curves of the wild and -overexpressed strain in the YPD medium were found to be almost identical. Compare to the -overexpressed strain, the wild strain showed a longer doubling time and lag phase in the presence of 20 mM furfural and 60 mM HMF, respectively. The real-time PCR results showed that furfural was much more potent than HMF in stimulating expression, but the cell growth patterns showed that 60 mM HMF was more toxic to yeast than 20 mM furfural. with overexpression appeared to confer higher tolerance to aldehyde inhibitors, thereby increasing the growth rate and ethanol production capacity of in an aldehyde-containing environment.