Microbe used to improve biofuel production
(Phys.org)—Biofuel production can be an expensive process that requires considerable use of fossil fuels, but a Missouri University of Science and Technology microbiologist's patented process could reduce the cost and the reliance on fossil fuels, while streamlining the process.
The process involves a microbe that thrives in extreme conditions.
Dr. Melanie Mormile, a professor of biological sciences at Missouri S&T, has found a particular bacterium, called "Halanaerobium hydrogeniformans," that can be used to streamline biofuel production. Because the bacterium thrives in high-alkaline, high-salt conditions, it can eliminate the need to neutralize the pH of the biomass, a step required in the alkali treatment of biomass for production of hydrogen fuel and other biofuels. Mormile and her fellow researchers have been awarded two patents for developing a biofuel production process that uses the bacterium.
"In the development of biofuels, a lot of energy is required to break down the biomass to the point where bacteria can ferment it to form ethanol or, in our case, hydrogen and other useful products," Mormile says.
The conventional method of biofuel production involves the steam blasting of switchgrass and straw to separate lignin, an unnecessary byproduct, from the cellulose that is needed to create the biofuel. The process requires electricity, produced by either coal or natural gas, to generate the steam. That process releases considerable amounts of carbon dioxide, while remaining dependent on fossil fuels. The degradation of the lignin produces compounds that inhibit fermentation and lead to overall low hydrogen yields.
Treating the switchgrass and straw with an alkaline substance removes the lignin with limited formation of the harmful compounds, but the resulting slurry is highly alkaline and very salty. Before the discovery of Halanaerobium hydrogeniformans, a neutralization step was required before the fermentation process could begin. Using Mormile's bacterium, that step can be eliminated.
"This shows promise in producing hydrogen from alkaline pre-treated biomass," Mormile says. "With alkaline pre-treatment, you don't have to apply heat, and using our bacterium will allow you to skip the neutralization process. It makes this a less expensive and more efficient process."
Mormile's team is getting results.
"We are seeing hydrogen production similar to a genetically modified organism and we haven't begun to tweak the genome of this bacterium yet."
Mormile is now looking for ways to optimize growth of the organism and minimize the cost. She is working with Dr. Oliver Sitton, associate professor of chemical and biochemical engineering at Missouri S&T, to optimize growth of the bacterium in a bioreactor.
"We have shown that we can produce hydrogen in a lab-scale reactor," Mormile says. "The next step in the project is to find the best growth medium and optimize the hydrogen production from this organism."
"We realize this isn't going to solve all the transportation fuel problems, but we'd like to see this develop into regionalized solutions," Mormile explains. "Farm communities could take agricultural waste, perform the alkaline pretreatment, feed it to an onsite reactor and produce hydrogen fuel directly for use on the farm."
Mormile studies extremophiles - life forms that exist in extreme conditions. The "Halanaerobium hydrogeniformans" bacterium used in Mormile's hydrogen fuel production study came from Soap Lake in Washington State.
Soap Lake is unique in that it has not turned over in more than 2,000 years because of its high salinity. Its water has the same pH as ammonia and is 10 times saltier than seawater.
"Normally, lakes turn over twice a year due to temperature changes in the water," Mormile explains. "Throughout the year, material like dead algae with all their nutrients accumulate at the bottom of the lake. During the summer months, the bottom of the lake stays cool while the surface gets warm, trapping the nutrients at the bottom. As fall approaches, the temperature throughout the whole lake becomes the same and mixing or turnover can occur."
Soap Lake's shape and high bottom salt content prevent it from turning over, trapping those nutrients.
"The bottom section of the lake contains so much salt it's like syrup," said Mormile.
In the future, Mormile hopes to return to Soap Lake to look for more new organisms.
"This process is only one step," Mormile says. "We know our bacteria can't break down cellulose, a crystalline molecule that provides structure for plants and trees. So we want to find bacterium that can break the cellulose down into smaller components that our fermenting bacteria can utilize."