Hot Discovery

A microorganism found in hot springs displays cellulosic ethanol potential
By Kris Bevill | March 05, 2012

Yellowstone National Park is home to more than 10,000 geysers, hot springs and other hydrothermal features, equal to about half of the world’s hydrothermal wonders. Recently, researchers from the U.S. DOE’s BioEnergy Science Center at Oak Ridge National Laboratory discovered a microorganism living within one of Yellowstone’s famous hot springs that could help unlock the secret of economical cellulosic ethanol production.

The bacterium, known as Caldicellulosiruptor obsidiansis, thrives in extremely hot temperatures and breaks down organic materials such as leaves and other debris in its natural environment. Scientists believe that if these characteristics can be transferred to biofuel production tanks, the microorganism could be very useful in consolidated bioprocessing, a production process that uses microorganisms to break down biomass and also produce ethanol. To test this potential, researchers conducted a series of experiments, evaluating proteins from C. obsidiansis grown on four materials ranging from simple sugar to pretreated switchgrass.

In a paper published in the Journal of Proteome Research, the researchers explained that testing simple substrates first provides an important basis of knowledge for researchers before they move on to more complex specimens such as switchgrass. “This progression helps us look at how proteins change given different carbon substrates,” ORNL researcher and study co-author Richard Giannone said. “One of the goals is to identify new proteins that we haven’t seen before. If an unknown protein doesn’t show up on the simple sugars or cellulose, but it shows up on the switchgrass, then we can say something about that gene or protein—that it responds to something the switchgrass is providing.” The researchers noted that switchgrass was selected for testing because they believe it is one of the most promising bioenergy crops in the U.S. due to its robustness and low ecological impact.

Through their testing, scientists found that the hot springs microorganism expressed a set of proteins that specifically breaks down the hemicellulose on switchgrass. They also found that, once inside the cell, it essentially turns on another function to process the C5 sugars further. The team plans to combine its measurements of the C. obsidiansis proteins with other technologies in order to obtain a holistic view of the organism, with the end goal of providing researchers with more complete information regarding the microorganism’s use in ethanol production.  —Kris Bevill