The answer to the looming fuel crisis in the 21st century may be found by thinking small, microscopic in fact. Microscopic organisms from bacteria and cyanobacteria, to fungi and microalgae, are biological factories that are proving to be efficient sources of inexpensive, environmentally friendly biofuels that can serve as alternatives to oil, according to research presented at the 109th General Meeting of the American Society for Microbiology.
“We have been charged to develop the next generation of cellulosic biofuels. When we successfully supply sources of energy to the grid from non-food, cellulosic, parts of plants we will mitigate the food versus fuel debate,” says Tim Donohue of the University of Wisconsin, Madison, one of two directors of Department of Energy Bioenergy Research Centers who spoke today in a session at the meeting.
When it comes to alternative fuels, currently ethanol is king. Almost all ethanol produced in the United States is fermented from readily available sugars in corn starch or corn kernels. Producing ethanol from corn has also come under much criticism lately, accused of being responsible for rising food prices.
Researchers are looking at alternate biomasses as food for microorganisms to ferment into ethanol. The most attractive are known as lignocellulosic biomass and include wood residues (including sawmill and paper mill discards), municipal paper waste, agricultural residues (including sugarcane bagasse), dedicated energy crops (like switchgrass) or the non-edible parts of corn like cobs, stalks or stover. The problem is, unlike corn starch, the sugars necessary for fermentation are trapped inside the lignocellulose part of this plant biomass. The key to ending the food versus fuel debate is unlocking the sugars trapped in cellulosic biomass.
To do that, some scientists have taken a page out of the playbook of the pharmaceutical industry. Pharmaceutical companies routinely use a process known as high throughput screening to rapidly test thousands of compounds for potential new drugs. Martin Keller at Oak Ridge National Laboratory, the DOE bioenergy research center director, and his lab have adapted the method to rapidly test poplar tree samples for their ability to give up sugars.
“We for the first time ever have developed a super-screening pipeline to handle thousands of samples. We took samples from approximately 1,300 poplar trees in the northwestern United States and used the screening pipeline to see if there was a difference in sugar release,” says Keller. “Trees can be very different. Some trees can be easier to digest, even within the same species.”
Keller is not sure why some poplars are more likely to give up their sugars than others. It could be genetic or the result of some environmental factor or a bit of both. They are now conducting experiments, growing poplar saplings under controlled environments to better understand.