Computing more efficient biofuel production

A new computational method to rapidly screen the effects of point mutations in bacteria has the potential to make biofuel production more efficient.

The conversion of fibrous plant waste such as corn stalks and wood shavings into fermentable simple sugars is a basic requirement of biofuel production, but the process is far from simple. Bacteria must break down tough leaves, stems and other cellulosic matter resistant to degradation to turn them into usable fuel.

Making bacteria more efficient at this process has the potential to make biofuels more affordable. One way to achieve this is to re-engineer the bacterial enzyme complexes, known as cellulosomes, which act as catalysts in the degradation process.

International research consortium CellulosomePlus is working on methods to produce these “designer cellulosomes” to make the degradation process more efficient and affordable. The consortium’s findings for one method have recently been published in the Journal of Chemical Physics.

The bacterium Clostridum thermocellum, which is capable of converting cellulose into ethanol, was the focus of the research. The scientists, from Poland, Ireland and Spain, developed a computational method to identify which point mutations – single amino acid replacements, would lead to stronger mechanical stability as well as higher thermodynamic stability.

Using all-atom computations, the researchers identified the mutations by systematically replacing all amino acids with either alanine or phenylalanine.

"One interesting result is that the mutations have a non-obvious impact on the internal structure of the protein and thus on the stabilities," said Mateusz Chwastyk, also one of the publication's authors.

"Our theoretical method seems to be a valid approximation for screening the effects of mutations in the mechanical and thermal stabilities of proteins," said Marek Cieplak, co-author of the paper who directs the Laboratory of Biological Physics at the Institute of Physics, Polish Academy of Sciences.

According to a statement from the American Institute of Physics, who publish the Journal of Chemical Physics, the proposed method is universal, can be applied to multiple mutations, and is currently used to explain properties of bacteria that live in extreme environments.