Scientists sponsored by the Office of Naval Research (ONR) have genetically modified a common soil bacteria to create electrical wires that not only conduct electricity, but are thousands of times thinner than a human hair.
As electronic devices increasingly touch all facets of people’s lives, there is growing appetite for technology that is smaller, faster and more mobile and powerful than ever before. Thanks to advances in nanotechnology (manipulating matter on an atomic or molecular scale), industry can manufacture materials only billionths of a meter in thickness.
The ONR-sponsored researchers—led by microbiologist Dr. Derek Lovley at the University of Massachusetts Amherst—say their engineered wires can be produced using renewable “green” energy resources like solar energy, carbon dioxide or plant waste; are made of non-toxic, natural proteins; and avoid harsh chemical processes typically used to create nanoelectronic materials.
“Research like Dr. Lovley’s could lead to the development of new electronic materials to meet the increasing demand for smaller, more powerful computing devices,” said Dr. Linda Chrisey, a program officer in ONR’s Warfighter Performance Department, which sponsors the research. “Being able to produce extremely thin wires with sustainable materials has enormous potential application as components of electronic devices such as sensors, transistors and capacitors.”
The centerpiece of Lovley’s work is Geobacter, a bacteria that produces microbial nanowires—hair-like protein filaments protruding from the organism—enabling it to make electrical connections with the iron oxides that support its growth in the ground. Although Geobacter naturally carries enough electricity for its own survival, the current is too weak for human use, but is enough to be measured with electrodes.
Lovley’s team tweaked the bacteria’s genetic makeup to replace two amino acids naturally present in the wires with tryptophan—which is blamed (incorrectly, some say) for the sleepiness that results from too much Thanksgiving turkey. Food allegations aside, tryptophan actually is very good at transporting electrons in the nanoscale.
“As we learned more about how the microbial nanowires worked, we realized it might be possible to improve on nature’s design,” said Lovley. “We rearranged the amino acids to produce a synthetic nanowire that we thought might be more conductive. We hoped that Geobacter might still form nanowires and double their conductivity.”
The results surpassed the team’s expectations as the synthetic, tryptophan-infused nanowires were 2,000 times more conductive than their natural counterparts. And they were more durable and much smaller, with a diameter of 1.5 nanometers (over 60,000 times thinner than a human hair)—which means that thousands of nanowires could possibly be stored in the tiniest spaces.
Lovley and Chrisey both say these ultra-miniature nanowires have numerous potential applications as electronic and computing devices continue to shrink in size. For example, they might be installed in medical sensors, where their sensitivity to pH changes can monitor heart rate or kidney function.
From a military perspective, the nanowires could feed electrical currents to specially engineered microbes to create butanol, an alternative fuel. This would be particularly useful in remote locations like Afghanistan, where fuel convoys are often attacked and it costs hundreds of dollars per gallon to ship fuel to warfighters.
Lovley’s nanowires also may play a crucial role in powering highly sensitive microbes (which could be placed on a silicon chip and attached to unmanned vehicles) that could sense the presence of pollutants, toxic chemicals or explosives.
“This is an exciting time to be on the cutting edge of creating new types of electronics materials,” said Lovley. “The fact that we can do this with sustainable, renewable materials makes it even more rewarding.”
Lovley’s research is part of ONR’s efforts in synthetic biology, which creates or re-engineers microbes or other organisms to perform specific tasks like improving health and physical performance. The field is a top ONR research priority because of its potential far-ranging impact on warfighter performance and fleet capabilities.
Synthetic biology is an emerging and rapidly evolving engineering discipline. Within the NCCR Molecular Systems Engineering, Bernese scientists have engineered a chemically switchable version of the light-driven proton pump proteorhodopsin – an essential tool for efficiently powering molecular factories and synthetic cells.
Synthetic biology is a highly interdisciplinary field, which combines biology, chemistry and physics with engineering. Its goal is to design molecular factories and synthetic cells with novel properties or functions for applications in healthcare, industry, or biological and medical research. Such artificial systems are in the nanometer scale and are built by combining and assembling existing, synthetic or engineered building blocks (e.g., proteins). Molecular systems have wide application ranges, e.g., for chemical compound synthesis, waste disposal, energy supply and medical diagnosis or treatment.
In this context, the NCCR Molecular Systems Engineering brings Swiss scientists from different disciplines together to stimulate innovation, and address existing and future challenges. The University of Bern is represented by the Fotiadis laboratory in the NCCR MSE.
Nanomachines for energy conversion
Energy-providing building blocks are essential to power molecular systems. Light-driven proton pumps such as the membrane protein proteorhodopsin represent excellent nanomachines for efficient energy conversion. Light energy, e.g., solar energy, is easily accessible and efficiently used by proteorhodopsin to establish proton gradients across membranes, which separate two different compartments. Such gradients can then be used to drive proton-driven building blocks of molecular systems, for example proton-driven transporters. Living cells commonly use proton gradients to power processes such as import and export of solutes and ions through transporters, and the synthesis of metabolites.
Eliminating the short-circuit
Using common methods for the assembly of proteorhodopsin, and membrane proteins in general, into containers such as liposomes or polymerosomes (i.e., spherical structures consisting of lipid or polymer membranes), symmetric integration in membranes is observed leading to short-circuit and failure in establishing a proton gradient. Therefore, members from the Fotiadis group, in particular Dr. Daniel Harder and Stephan Hirschi, together with colleagues from the NCCR MSE have implemented a chemical on-off switch into proteorhodopsin, thus extending its versatility and allowing the establishment of an asymmetric distribution of functional proteorhodopsin proteins in membranes by selectively deactivating one of the two possible orientations.
This engineered version of proteorhodopsin represents the first light-driven proton pump and energizing-building block that can be activated and deactivated chemically to meet the requirements of the molecular system. «Possible applications of this versatile energy-providing building block in specific molecular factories represent the light- and solar-powering of the production of molecules such as life’s universal energy currency ATP (adenosine triphosphate) and of the bioremediation of pollutants such as antibiotics in water resources», says Fotiadis. The study was published in the renowned scientific journal «Angewandte Chemie International Edition».
Researchers at the University of California San Diego and the Massachusetts Institute of Technology (MIT) have come up with a strategy for using synthetic biology in therapeutics. The approach enables continual production and release of drugs at disease sites in mice while simultaneously limiting the size, over time, of the populations of bacteria engineered to produce the drugs. The findings are published in the July 20 online issue of Nature.
UC San Diego researchers led by Jeff Hasty, a professor of bioengineering and biology, engineered a clinically relevant bacterium to produce cancer drugs and then self-destruct and release the drugs at the site of tumors. The team then transferred the bacterial therapy to their MIT collaborators for testing in an animal model of colorectal metastasis. The design of the therapy represents a culmination of four previous Nature papers from the UC San Diego group that describe the systematic development of engineered genetic clocks and synchronization. Over the years, the researchers have employed a broad approach that spans the scales of synthetic biology,
The new study offers a therapeutic approach that minimizes damage to surrounding cells.
“In synthetic biology, one goal of therapeutics is to target disease sites and minimize damage,” said UC San Diego bioengineering and biology professor Jeff Hasty. He wondered if a genetic “kill” circuit could be engineered to control a population of bacteria in vivo, thus minimizing their growth. “We also wanted to deliver a significant therapeutic payload to the disease site.”
Scientists are trying to find a new way to produce the nutritional fatty acids called Omega 3 that are currently sourced from fish oil from the world’s declining natural fish stocks.
In a groundbreaking branch of new science – synthetic biology – the team at The University of Nottingham’s Synthetic Biology Research Centre are working with biotechnology company CHAIN Biotech and industry partner Calysta, Inc. to develop microbial technology that uses microorganisms to ferment methane gas into valuable nutritional supplements.
The pioneering project is called PUFA (polyunsaturated fatty acids). It will run for a year and is being funded by industrial biotechnology catalyst grants from InnovateUK and the BBSRC with potential further significant scaling up investment from Calysta, a sustainable nutrition company based in the US.
Omega 3 fatty acids are essential for the growth, development and healthy maintenance of the brain and are incorporated in many kinds of foods and infant nutrition products as well as animal feed and health products. Currently Omega 3 fatty acids are sourced from fish oils, but wild fish stocks are under pressure and there is an urgency to find alternative sources that are both sustainable and economical.
UCLA biochemists have devised a clever way to make a variety of useful chemical compounds, which could lead to the production of biofuels and new pharmaceuticals.
“The idea of synthetic biology is to redesign cells so they will take sugar and run it through a series of chemical steps to convert it into a biofuel or a commodity chemical or a pharmaceutical,” said James Bowie, a professor of chemistry and biochemistry in the UCLA College, and senior author of the new research. “However, that’s extremely difficult to do. The cell protests. It will take the sugar and do other things with it that you don’t want, like build cell walls, proteins and RNA molecules. The cell fights us the whole way.”
As an alternative, Bowie and his research team have developed a promising approach he calls synthetic biochemistry that bypasses the need for cells.
“We want to do a particular set of chemical transformations — that’s all we want — so we decided to throw away the cells and just build the biochemical steps in a flask,” Bowie said. “We eliminate the annoying cell altogether.”
Synthetic biology technique could make it safer to put engineered microbes to work outside the lab
Many research teams are developing genetically modified bacteria that could one day travel around parts of the human body, diagnosing and even treating infection. The bugs could also be used to monitor toxins in rivers or to improve crop fertilization.
However, before such bacteria can be safely let loose, scientists will need to find a way to prevent them from escaping into the wider environment, where they might grow and cause harm.
Berkeley Lab Scientists Believe Biomanufacturing a Key to Long-term Manned Space Missions
Does synthetic biology hold the key to manned space exploration of the Moon and Mars? Berkeley Lab researchers have used synthetic biology to produce an inexpensive and reliable microbial-based alternative to the world’s most effective anti-malaria drug, and to develop clean, green and sustainable alternatives to gasoline, diesel and jet fuels. In the future, synthetic biology could also be used to make manned space missions more practical.
“Not only does synthetic biology promise to make the travel to extraterrestrial locations more practical and bearable, it could also be transformative once explorers arrive at their destination,” says Adam Arkin, director of Berkeley Lab’s Physical Biosciences Division (PBD) and a leading authority on synthetic and systems biology.
“During flight, the ability to augment fuel and other energy needs, to provide small amounts of needed materials, plus renewable, nutritional and taste-engineered food, and drugs-on-demand can save costs and increase astronaut health and welfare,” Arkin says. “At an extraterrestrial base, synthetic biology could make even more effective use of the catalytic activities of diverse organisms.”
Arkin is the senior author of a paper in the Journal of the Royal Society Interface that reports on a techno-economic analysis demonstrating “the significant utility of deploying non-traditional biological techniques to harness available volatiles and waste resources on manned long-duration space missions.” The paper is titled “Towards Synthetic Biological Approaches to Resource Utilization on Space Missions.” The lead and corresponding author is Amor Menezes, a postdoctoral scholar in Arkin’s research group at the University of California (UC) Berkeley. Other co-authors are John Cumbers and John Hogan with the NASA Ames Research Center.
One of the biggest challenges to manned space missions is the expense. The NASA rule-of-thumb is that every unit mass of payload launched requires the support of an additional 99 units of mass, with “support” encompassing everything from fuel to oxygen to food and medicine for the astronauts, etc. Most of the current technologies now deployed or under development for providing this support are abiotic, meaning non-biological. Arkin, Menezes and their collaborators have shown that providing this support with technologies based on existing biological processes is a more than viable alternative.