Engineered E. Coli strain boosts biohydrogen production from sugar 140 times compared with wild type
Scientists at the Texas A&M University's chemical engineering department have genetically engineered the Escherichia Coli bacterium and boosted its capacity to produce biohydrogen from sugar. Professor Thomas Woods, of the Artie McFerrin Department of Chemical Engineering, modified a strain which produces up to 140 times more hydrogen than is created in a naturally occurring process. His findings about the potential of this gaseous biofuel are presented in an open access article in Microbial Biotechnology. The professor sees a future based on local and decentralised biohydrogen production, with the sugar feedstock being transported to mini-factories where the bacteria ferment it into the pure energy-rich gas.
Wood acknowledges that there is still much work to be done before his research translates into any kind of commercial application, but his initial success could prove to be a significant stepping stone on the path to the hydrogen-based economy that many believe could contribute greatly to cleaner mobility, the uptake of renewable, bio-based energy and strengthen energy security.
Renewable, clean and efficient hydrogen is the key ingredient in fuel-cell technology, which has the potential to power everything from portable electronics to automobiles and even entire power plants. Today, most of the hydrogen produced globally is created by a process known as electrolysis through which hydrogen is separated from the oxygen. But the process is expensive and requires vast amounts of primary energy - one of the chief reasons why the technology has yet to catch on. Alternatively, hydrogen can be produced by reforming fossil fuels (oil, coal, natural gas), but in that case the fuel isn't renewable nor clean and would lead to large amounts of greenhouse gas emissions during its production. The cleanest and most efficient way to produce hydrogen is from biomass - either via gasification or fermentation (previous post).
Wood's work with E. coli and biohydrogen is on track to solve the current problems surrounding hydrogen production. It takes the fermentation pathway (schematic, click to enlarge). By selectively deleting six specific genes in E. coli's DNA, the scientist and his collegues have basically transformed the bacterium into a mini biohydrogen-producing factory that's powered by sugar. Scientifically speaking, Wood has enhanced the bacteria's naturally occurring glucose-conversion process on a massive scale.
energy :: sustainability :: biomass :: bioenergy :: biofuels :: bacteria :: sugar :: fermentation :: efficiency :: biohydrogen ::
One of the most difficult things about chemical engineering is how you get the product, Wood explained. In this case, it's very easy because the hydrogen is a gas, and it just bubbles out of the solution. You just catch the gas as it comes out of the glass. That's it. You have pure hydrogen.
Decentralised production
There also are other benefits. As might be expected, the cost of building an entirely new pipeline to transport hydrogen is a significant deterrent in the utilization of hydrogen-based fuel cell technology. In addition, there is also increased risk when transporting hydrogen. The solution, Wood believes, is converting hydrogen on site.
The main thing we think is you can transport things like sugar, and if you spill the sugar there is not a huge catastrophe, Wood said. The idea is to make the hydrogen where you need it.
Of course, all of this is down the road. Right now, Wood remains busy in the lab, working on refining a process that's already hinted at its incredible potential. The goal, he said, is to continue to get more out of less.
Schematic: sketch of fermentative hydrogen production in Escherichia coli. Hydrogen is produced from formate by the formate hydrogen lyase (FHL) system [hydrogenase 3 and formate dehydrogenase-H (FDHH)], which is activated by FhlA (that is regulated by Fnr) and repressed by HycA. Evolved hydrogen is consumed through the hydrogen uptake activity of hydrogenase 1 and hydrogenase 2. Formate is exported by FocA and/or FocB and is metabolized by formate dehydrogenase-N (FDHN) which is linked with nitrate reductase A and formate dehydrogenase-O (FDHO). Cyanobacterial hydrogenases (HoxEFUYH) derived from Synechocystis sp. PCC 6803 inhibit the activity of E. coli hydrogenase 1 and hydrogenase 2 resulting in enhanced hydrogen yield.
References:
Toshinari Maeda, Viviana Sanchez-Torres, Thomas K. Wood, "Metabolic engineering to enhance bacterial hydrogen production" [open access], Microbial Biotechnology 1 (1), 2008, 30–39, doi:10.1111/j.1751-7915.2007.00003.x
Texas A & M University: Wood envisions "E. Coli" as future source of energy - January 29, 2008.
Biopact: Biohydrogen, a way to revive the 'hydrogen economy'? - August 20, 2006
Article continues
Wood acknowledges that there is still much work to be done before his research translates into any kind of commercial application, but his initial success could prove to be a significant stepping stone on the path to the hydrogen-based economy that many believe could contribute greatly to cleaner mobility, the uptake of renewable, bio-based energy and strengthen energy security.
Renewable, clean and efficient hydrogen is the key ingredient in fuel-cell technology, which has the potential to power everything from portable electronics to automobiles and even entire power plants. Today, most of the hydrogen produced globally is created by a process known as electrolysis through which hydrogen is separated from the oxygen. But the process is expensive and requires vast amounts of primary energy - one of the chief reasons why the technology has yet to catch on. Alternatively, hydrogen can be produced by reforming fossil fuels (oil, coal, natural gas), but in that case the fuel isn't renewable nor clean and would lead to large amounts of greenhouse gas emissions during its production. The cleanest and most efficient way to produce hydrogen is from biomass - either via gasification or fermentation (previous post).
Wood's work with E. coli and biohydrogen is on track to solve the current problems surrounding hydrogen production. It takes the fermentation pathway (schematic, click to enlarge). By selectively deleting six specific genes in E. coli's DNA, the scientist and his collegues have basically transformed the bacterium into a mini biohydrogen-producing factory that's powered by sugar. Scientifically speaking, Wood has enhanced the bacteria's naturally occurring glucose-conversion process on a massive scale.
These bacteria have 5,000 genes that enable them to survive environmental changes. When we knock things out, the bacteria become less competitive. We haven't given them an ability to do something. They don't gain anything here; they lose. The bacteria that we're making are less competitive and less harmful because of what's been removed. - Professor Thomas WoodsWith sugar as its main power source, this strain of E. coli can now take advantage of existing and ever-expanding scientific processes aimed at producing sugar from energy crops.
A lot of people are working on converting something that you grow into some kind of sugar. We want to take that sugar and make it into hydrogen. We're going to get sugar from some crop somewhere. We're going to get some form of sugar-like molecule and use the bacteria to convert that into hydrogen. - Professor WoodsBiological methods such as this - E. coli producing hydrogen through a fermentative process - are likely to reduce energy costs since these processes don't require extensive heating or electricity. They are an alternative to thermochemical and electrolysis-based hydrogen production:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: bacteria :: sugar :: fermentation :: efficiency :: biohydrogen ::
One of the most difficult things about chemical engineering is how you get the product, Wood explained. In this case, it's very easy because the hydrogen is a gas, and it just bubbles out of the solution. You just catch the gas as it comes out of the glass. That's it. You have pure hydrogen.
Decentralised production
There also are other benefits. As might be expected, the cost of building an entirely new pipeline to transport hydrogen is a significant deterrent in the utilization of hydrogen-based fuel cell technology. In addition, there is also increased risk when transporting hydrogen. The solution, Wood believes, is converting hydrogen on site.
The main thing we think is you can transport things like sugar, and if you spill the sugar there is not a huge catastrophe, Wood said. The idea is to make the hydrogen where you need it.
Of course, all of this is down the road. Right now, Wood remains busy in the lab, working on refining a process that's already hinted at its incredible potential. The goal, he said, is to continue to get more out of less.
Take your house, for example. The size of the reactor that we'd need today if we implemented this technology would be less than the size of a 250-gallon fuel tank found in the typical east-coast home. I'm not finished with this yet, but at this point if we implemented the technology right now, you or a machine would have to shovel in about the weight of a man every day so that the reactor could provide enough hydrogen to take care of the average American home for a 24-hour period. - Professor WoodsThe scientists are now trying to make bacteria that don't require 80 kilograms but closer to 8 kilograms.
Schematic: sketch of fermentative hydrogen production in Escherichia coli. Hydrogen is produced from formate by the formate hydrogen lyase (FHL) system [hydrogenase 3 and formate dehydrogenase-H (FDHH)], which is activated by FhlA (that is regulated by Fnr) and repressed by HycA. Evolved hydrogen is consumed through the hydrogen uptake activity of hydrogenase 1 and hydrogenase 2. Formate is exported by FocA and/or FocB and is metabolized by formate dehydrogenase-N (FDHN) which is linked with nitrate reductase A and formate dehydrogenase-O (FDHO). Cyanobacterial hydrogenases (HoxEFUYH) derived from Synechocystis sp. PCC 6803 inhibit the activity of E. coli hydrogenase 1 and hydrogenase 2 resulting in enhanced hydrogen yield.
References:
Toshinari Maeda, Viviana Sanchez-Torres, Thomas K. Wood, "Metabolic engineering to enhance bacterial hydrogen production" [open access], Microbial Biotechnology 1 (1), 2008, 30–39, doi:10.1111/j.1751-7915.2007.00003.x
Texas A & M University: Wood envisions "E. Coli" as future source of energy - January 29, 2008.
Biopact: Biohydrogen, a way to revive the 'hydrogen economy'? - August 20, 2006
Article continues
Wednesday, January 30, 2008
Nobel Laureate Steven Chu sees a biofuels revolution
Late last year, Professor Steven Chu held a talk at the World Affairs Council of Northern California in which he explains his work on advanced generations of biofuels and how science and technology could make the green fuels part of an entirely new, sustainable energy paradigm. Some of the world's best scientists - amongst them 43 Nobel Laureates - are working in Chu's Lab on bioenergy, renewables and global warming because the energy and climate challenges we face require a Manhattan Project approach, he says.
Professor Chu, who won the Nobel Prize for Physics in 1997, says no one nation can effectively reverse the growing problems caused by our changing climate and growing energy consumption. Coordinated global efforts - between governments, international organisations, and civil society - can help us conserve and develop new energy resources, as well as ensure the continued growth of emerging and developed nations.
Biofuels might play an important role in this development. Rapid scientific advances in biotechnology and plant sciences make the efficient production of renewable energy from non-food biomass - that is, cellulose, the world's most abundant organic compound - possible. Increases in the photosynthetic efficiency of plants will soon emerge, but the ultimate challenge will be to develop 'synthetic plants' with very high conversion efficiencies. Such artificial photosynthetic machines, inspired by nature, will make hydrocarbons out of sunlight, water and carbon dioxide.
But before we get there, emerging advanced biofuels are likely to be applied on a world changing scale. The Nobel Laureate questions many of the conventional neo-malthusian views on the availability of natural resources. Instead, he says, there is a large enough carrying capacity - land, water, sunshine, soil and seeds - and institutional capacity to generate highly efficient, genuinely sustainable biofuels, food and fiber products for the population. With enough political will and the right policy choices, a secure energy and climate future based on biofuels becomes possible.
Current biofuels come with their problems and the dependence on food crops is not sustainable nor desirable. Scientists like Chu are therefor working to develop new biomass conversion technologies that could end the food versus fuel dilemma, and serve communities in poor countries. The Nobel Laureate refers to an energy crop like Miscanthus, which yields 10 times more fuel than corn, requires no fertilizer or water, reduces erosion by a factor of 100 and requires no till. It grows its own nitrogen fixing bacteria and improves soil properties. These crops will become the feedstocks of the future. Chu is working on novel and efficient ways to breakdown the cellulose of these plants, which would make biofuels abdunant and cheap. Genomics and genetic engineering of microbes (such as those found in termite guts) will accomplish the task.
In his talk, Chu also referred to the most comprehensive report written so far about the future of energy this century, the panel for which he co-chaired. It is the report titled 'Lighting the Way: Toward A Sustainable Energy Future', published by 13 National Science Academies, written by the world's leading energy scientists and discussed here. In it, the scientists warn for a potential energy crisis of unprecedented proportions, and call for the immediate implementation of new technologies and fuel sources - like biofuels and carbon-negative bioenergy - that can avert it. They conclude that biofuels hold great promise for simultaneously addressing climate-change and energy-security concerns. In all these efforts, the interests and needs of the poor - some 2 billion people without access to modern energy - should be met first.
Steven Chu is a Professor of Physics and Molecular and Cellular Biology at the University of California, Berkeley and director of the Lawrence Berkeley National Laboratory. Video courtesy of Fora.tv: Steven Chu, A New Energy Paradigm. Fora.tv hosts transcripts, downloads and a discussion forum for this video.
ethanol :: biodiesel :: biobutanol :: biomass :: bioenergy :: biofuels :: energy :: sustainability :: Africa ::
Article continues
posted by Biopact team at 10:00 PM 1 comments links to this post