"Here at the EBI and other places in the biofuel world, people are trying to engineer microbes that can use both," said University of Illinois microbiologist Isaac Cann. "Most of the time what they do is they take genes from different locations and try and stitch all of them together to create a pathway that will allow that microbe to use the other sugar."
Cann and Rod Mackie, also a U of I microbiologist, have been doing research at the Energy Biosciences Institute on an organism that they think could be used to solve this problem.
Mackie, a long-distance runner, found the microbe in the garbage dump of a canning plant while running in Hoopeston, Ill., in 1993. He noticed that the ground was literally bubbling with microbial activity and took samples. He and his son Kevin, who was in high school at the time, isolated microbes from the samples.
Among these was a bacterium that was later named Caldanaerobius polysaccharolyticus. "We found many exciting enzymes from this organism," said Cann, who joined the project when he came to Mackie's lab as a postdoctoral researcher.
Specifically, the bacterium contains all of the proteins and enzymes needed to break down xylan, which is the most common hemicellulose, and then to transport the fragments into the cell and metabolize them. All of the genes are located in a single cluster on the microbe's genome.
"So instead of taking a piece from here and from there and stitching them together, we can just take this part of the gene," Cann explained. "You can cut this and put it into another microbe."
On the surface of the cell, there is an enzyme that cuts the xylan into small pieces and a protein that binds to the pieces and brings them inside the cell. Enzymes within the cell metabolize the sugar.
The reason that this microbe, unlike most others used to make biofuels, is able to degrade xylan is that it has evolved an enzyme that allows it to remove the side chains, or decorations, that are part of xylan's structure. They hinder the degradation process by preventing complete accessibility of the enzymes to the sugar chain.
Once the side chains have been removed, another enzyme in the microbe breaks the sugar chain down into single sugars, or xylose. Other enzymes within the cell then metabolize the xylose.
Having the enzymes next to each other on the genome is convenient for scientists who are working on engineering microbes that can degrade both cellulose and hemicellulose. The cluster could be designed as a cassette and put into a microbe that normally degrades only cellulose.
Moreover, being next to each other allows them to work efficiently. "You have a set of enzymes that have co-evolved," Cann explained. "If they have co-evolved over millions of years, it means they have been fine-tuned to work together."
Another advantage of Caldanaerobius polysaccharolyticus is that it is a thermophilic bacterium, and its enzymes are resistant to temperatures as high as 70 degrees Celsius. Biofuel fermentation is usually done at 37 degrees Celsius, a temperature at which most microbes can survive. This means that the material in the fermentation vats is easily contaminated.
The next step for Cann and his collaborators is to develop techniques for transferring this gene cluster, which is quite large, into microbes.
The research was recently published in the Journal of Biological Chemistry and is available at http://www.jbc.org/content/287/42/34946.full?sid=3f2242e5-c278-4d3e-b16c-1c6f79b01f4b. Yejun Han, Vinayak Agarwal, Dylan Dodd, Jason Kim, Brian Bae, and Satish K. Nair are co-authors.
The Energy Biosciences Institute is a four-partner research collaboration that includes the University of Illinois, the University of California at Berkeley, Lawrence Berkeley National Laboratory, and BP, the energy company that funds the work. It is dedicated to applying the biological sciences to the challenges of producing sustainable, renewable energy for the world.
Susan Jongeneel | EurekAlert!
Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
22.02.2018 | Life Sciences
22.02.2018 | Physics and Astronomy
22.02.2018 | Earth Sciences