Researchers are exploring whether these ubiquitous fluorinated molecules might worsen infections or hamper vaccine effectiveness.
Image credit: Shutterstock/Dmitry Naumov.
Edited* by Arnold L. Demain, Drew University, Madison, NJ, and approved March 27, 2013 (received for review February 5, 2013)
Abstract
The global demand for food could double in another 40 y owing to growth in the population and food consumption per capita. To meet the world’s future food and sustainability needs for biofuels and renewable materials, the production of starch-rich cereals and cellulose-rich bioenergy plants must grow substantially while minimizing agriculture’s environmental footprint and conserving biodiversity. Here we demonstrate one-pot enzymatic conversion of pretreated biomass to starch through a nonnatural synthetic enzymatic pathway composed of endoglucanase, cellobiohydrolyase, cellobiose phosphorylase, and alpha-glucan phosphorylase originating from bacterial, fungal, and plant sources. A special polypeptide cap in potato alpha-glucan phosphorylase was essential to push a partially hydrolyzed intermediate of cellulose forward to the synthesis of amylose. Up to 30% of the anhydroglucose units in cellulose were converted to starch; the remaining cellulose was hydrolyzed to glucose suitable for ethanol production by yeast in the same bioreactor. Next-generation biorefineries based on simultaneous enzymatic biotransformation and microbial fermentation could address the food, biofuels, and environment trilemma.
Footnotes
↵1C.Y. and H.C. contributed equally to this work.
- ↵2To whom correspondence should be addressed. E-mail: ypzhang{at}vt.edu.
Author contributions: C.Y., H.C., and Y.-H.P.Z. designed research; C.Y. and H.C. performed research; S.M., H.M., and X.-Z.Z. contributed new reagents/analytic tools; C.Y., H.C., N.S., J.L., and Y.-H.P.Z. analyzed data; and H.C. and Y.-H.P.Z. wrote the paper.
Conflict of interest statement: The authors have filed a provisional patent disclosure (Zhang Y-HP, Chen H. Conversion of cellulose to starch through an in vitro synthetic enzymatic pathway. Filed on December 17, 2012.).
↵*This Direct Submission article had a prearranged editor.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1302420110/-/DCSupplemental.
Nonfood biomass to starch
Sign up for Article Alerts
Jump to section
You May Also be Interested in
Recent experiments and simulations are starting to answer some fundamental questions about how life came to be.
Image credit: Shutterstock/Radoslaw Lecyk.
Archaeologists have long tried to define the transition between the two time periods.
Image credit: Ceri Shipton.
Adam Mastroianni and Daniel Gilbert explore why conversations almost never end when people want them to.
A study finds that giant pandas roll in horse manure to increase their cold tolerance.
Image credit: Fuwen Wei.