New yeast strain produces higher ethanol volume from pine

By Matt Soberg | November 22, 2011

University of Georgia researchers developed new yeast that produces higher volume of ethanol from pine with results published on Nov. 10 in the online journal Biotechnology for Biofuels. The research concluded that pine conversion using the new yeast improves the “overall economic viability of a pine-to-ethanol conversion process.”

The researchers, Joy Doran-Peterson, associate professor of microbiology, and G. Matt Hawkins, doctoral candidate, engineered and adapted the yeast strain Saccaromyces cerevisiae, commonly used in corn ethanol production, to better bioconvert softwoods, such as pine. The researchers grew the new yeast in increasingly inhospitable conditions during a two-year research period, resulting in yeast capable of producing ethanol from pine containing 17.5 percent solid biomass, according to the research.

“The basic idea is that we’re trying to get the yeast to make as much ethanol as it can, as fast as it can, while minimizing costs associated with cleaning or washing the pretreated pine,” Doran-Peterson said.“With our process, no additional clean-up steps are required before the pine is fermented.

The research focused on overcoming softwood challenges resulting from the pretreatment process, including formation of materials that kill the hardiest of ethanol producing yeasts. “The problem with using pine as a substrate is that when you pre-treat, it generates inhibitory compounds preventing it from reaching the maximum ethanol yield,” Hawkins said. Our yeast is able to survive and produce ethanol at higher solid concentrations, which means you can put more wood in the fermentation and receive more theoretical ethanol yield,

The researchers noted that softwoods, including pine, “are the dominant source of lignocellulosic biomass in the Northern hemisphere and have been investigated world-wide as a renewable substrate for cellulosic ethanol production.” An efficient pine-to-ethanol conversion process could benefit the cellulosic ethanol industry.  

“Companies are interested in producing ethanol from woody biomass such as pine, but it is a notoriously difficult material for fermentations, Doran-Peterson said. “The big plus for softwoods, including pine, is that they have a lot of sugar that yeast can use. Yeast are currently used in ethanol production from corn or sugarcane, which are much easier materials for fermentation; our process increases the amount of ethanol that can be obtained from pine,” she added.