Advanced BioFuels USA

by Jules Bernstein (University of California – Riverside/Phys.Org) A new study reveals how bacteria control the chemicals produced from consuming ‘food.’ The insight could lead to organisms that are more efficient at converting plants into biofuels.

The study, authored by scientists at UC Riverside and Pacific Northwest National Laboratory, has been published in the Journal of the Royal Society Interface.

In the article, the authors describe mathematical and computational modeling, artificial intelligence algorithms and experiments showing that cells have failsafe mechanisms preventing them from producing too many metabolic intermediates.

Metabolic intermediates are the chemicals that couple each reaction to one another in metabolism. Key to these control mechanisms are enzymes, which speed up chemical reactions involved in biological functions like growth and energy production.

“Cellular metabolism consists of a bunch of enzymes. When the cell encounters food, an enzyme breaks it down into a molecule that can be used by the next enzyme and the next, ultimately generating energy,” explained study co-author, UCR adjunct math professor and Pacific Northwest National Laboratory computational scientist William Cannon.

The enzymes cannot produce an excessive amount of metabolic intermediates. They produce an amount that is controlled by how much of that product is already present in the cell.

“This way the metabolite concentrations don’t get so high that the liquid inside the cell becomes thick and gooey like molasses, which could cause cell death,” Cannon said.

One of the barriers to creating biofuels that are cost competitive with petroleum is the inefficiency of converting plant material into ethanol. Typically, E. coli bacteria are engineered to break down lignin, the tough part of plant cell walls, so it can be fermented into fuel.

Mark Alber, study co-author and UCR distinguished math professor, said that the study is a part of the project to understand the ways bacteria and fungi work together to affect the roots of plants grown for biofuels.

“One of the problems with engineering bacteria for biofuels is that most of the time the process just makes the bacteria sick,” Cannon said. “We push them to overproduce proteins, and it becomes uncomfortable—they could die. What we learned in this research could help us engineer them more intelligently.”

Knowing which enzymes need to be prevented from overproducing can help scientists design cells that produce more of what they want and less of what they don’t.  READ MORE

Samuel Britton et al, Enzyme activities predicted by metabolite concentrations and solvent capacity in the cell, Journal of The Royal Society Interface (2020). DOI: 10.1098/rsif.2020.0656