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Sodium hydroxide pretreatment of genetically modified switchgrass for improved enzymatic release of sugars
- Wang, Ziyu, Li, Ruyu, Xu, Jiele, Marita, Jane M., Hatfield, Ronald D., Qu, Rongda, Cheng, Jay J.
- Bioresource technology 2012 v.110 pp. 364
- Panicum virgatum, alkalis, biomass, biotransformation, cell walls, cellulases, commercialization, coumarate-CoA ligase, enzymatic hydrolysis, gene expression regulation, genes, lignin, pretreatment, sodium hydroxide, sugars, transgenic plants, xylanases
- Overcoming biomass recalcitrance to bioconversion is crucial for cellulosic biofuels commercialization. In this study, Alamo switchgrass (Panicum virgatum L.) was genetically transformed to suppress the expression of 4-coumarate-CoA ligase (4CL). The transgenic plants were determined to have lignin content reductions of up to 5.8%. The ratios of acid soluble lignin (ASL) to acid insoluble lignin (AIL) and syringyl/guaiacyl (S/G) in transgenic plants were 21.4–64.3% and 11.8–164.5%, respectively, higher than those of conventional biomass. Both conventional and transgenic plants were pretreated with 0.5%, 1%, and 2% (w/v) NaOH for 15, 30, and 60min at 121°C, followed by enzymatic hydrolysis with commercial cellulases and xylanases. At the optimal conditions, the glucan and xylan conversion efficiency in the best transgenic plants were 16% and 18% higher than the conventional plant, respectively. The results show that down-regulation of 4CL gene promoted enzymatic hydrolysis of plant cell walls following a mild alkali pretreatment.