Consolidated Pretreatment and Hydrolysis of Plant Biomass Expressing Cell Wall Degrading Enzymes

• Published in: Bioenergy research Vol. 4; no. 4; pp. 276 - 286
• Main Authors: Zhang, Dongcheng, VanFossen, Amy L., Pagano, Ryan M., Johnson, Jeremy S., Parker, Matthew H., Pan, Shihao, Gray, Benjamin N., Hancock, Elaina, Hagen, Daniel J., Lucero, Héctor A., Shen, Binzhang, Lessard, Philip A., Ely, Cairn, Moriarty, Meghan, Ekborg, Nathan A., Bougri, Oleg, Samoylov, Vladimir, Lazar, Gabor, Raab, R. Michael
• Format: Journal Article
• Language: English
• Published: New York Springer-Verlag 01-12-2011; Springer; Springer Nature B.V
• Subjects: Alternative energy sources; Analysis; Biodiesel fuels; Biofuels; Biomass; Biomass energy; Biomedical and Life Sciences; Biotechnology; Cellulose; Corn; Costs; Dextrose; Enzymes; Ethanol; Ethyl alcohol; Fermentation; Food; Genetic engineering; Genetically engineered foods; Genetically modified crops; Glucose; Hydrolysis; Life Sciences; Lignocellulose; Maize; Plant biomass; Plant Breeding/Biotechnology; Plant Ecology; Plant Genetics and Genomics; Plant Sciences; Plants (organisms); Raw materials; Saccharomyces cerevisiae; Stover; Studies; Sugar; Transgenic; Transgenic plants; Wood Science & Technology; Yeasts; Zea mays; United States > US; Hydrolysis; Yeast; Corn stover; Enzyme; Simultaneous saccharification and fermentation (SSF); Biomass; Pretreatment; Biofuels; Fermentation; Cell wall; Genetic modification
• DOI: 10.1007/s12155-011-9138-2
• EISSN: 1939-1242
• ISSN: 1939-1234

Significant amounts of cell wall degrading (CWD) enzymes are required to degrade lignocellulosic biomass into its component sugars. One strategy for reducing exogenous enzyme production requirements is to produce the CWD enzymes
in planta
. For this work, various CWD enzymes were expressed in maize (
Zea mays
). Following growth and dry down of the plants, harvested maize stover was tested to determine the impact of the expressed enzymes on the production of glucose and xylose using different exogenous enzyme loadings. In this study, a consolidated pretreatment and hydrolysis process consisting of a moderate chemical pretreatment at temperatures below 75°C followed by enzymatic hydrolysis using an in-house enzyme cocktail was used to evaluate engineered transgenic feedstocks. The carbohydrate compositional analysis showed no significant difference in the amounts of glucan and xylan between the transgenic maize plants expressing CWD enzyme(s) and the control plants. Hydrolysis results demonstrated that transgenic plants expressing CWD enzymes achieved up to 141% higher glucose yield and 172% higher xylose yield over the control plants from enzymatic hydrolysis under the experimental conditions. The hydrolytic performance of a specific xylanase (XynA) expressing transgenic event (XynA.2015.05) was heritable in the next generation, and the improved properties can be achieved even with a 25% reduction in exogenous enzyme loading. Simultaneous saccharification and fermentation of biomass hydrolysates from two different transgenic maize lines with yeast (
Saccharomyces cerevisiae
D5A) converted 65% of the biomass glucan into ethanol, versus only a 42% ethanol yield with hydrolysates from control plants, corresponding to a 55% improvement in ethanol production.