Soil and plants glow around a land mine. Oak Ridge National Labs developed a bacteria that glowed under UV light after exposure to land mines. Recent work at iGEM hopes to improve upon the system.

Synthetic biology and students are mixing with explosive results. Remember the international Genetically Engineered Machine competition we told you was coming? It happened, and while there were many amazing and interesting projects (we’ll have a story on that later) there’s one team that’s already gotten a lot of media hype. BBC News reported that students from University of Edinburgh have developed a new strand of bacteria that will glow green in the presence of land mines. That’s very close to the truth. The Edinburgh team has made some great strides in that direction but haven’t produced a working system yet. What they have made is a kooky (maybe even embarrassingly silly) video about their work. Check it out after the break.

Oak Ridge National Labs was developing a land mine detecting bacteria ten years ago that required UV illumination (the above image shows their results). The Edinburgh team hopes to improve upon the ORNL system by eliminating the need for complex lighting. Using the BioBrick parts provided by MIT, the Scottish team genetically modified a strand of bacteria (Rhodococcus rhodochrous) so that it will react to increased levels of nitrites in soils – this indicates the presence of TNT or RDX, important ingredients in most land mines. If successful, the Edinburgh bacteria could be mixed in a solution and sprayed on fields, allowing workers to locate and disarm the mines. With tens of thousands of deaths occurring each year due to abandoned mines and unexploded ordinance, this project has potential of saving the limbs and lives of victims, many of whom would be children. The project’s not done, but it certainly is an amazing endeavor for a group of college students.

[photo credit: Oak Ridge National Labs]
[video credit: University of Edinburgh iGEM team]

The motion of bacteria caused this notched cog to rotate. The yellow circled dot is a reference point.

Many proposed concepts of harnessing bacterial motion actually involve harnessing the bacteria with tiny molecular strings. Others want to use the “carrot” approach, encouraging bacteria to push a rotor by making it appealing somehow. The University of Rome team’s work shows that we can get power without all this effort. Just the natural movement of E. coli is enough to turn an asymmetric cog. While they will undoubtedly also pursue the harness or carrot approach, the Italian team has proven the most basic concept works. This means that we have an entirely new potential source of power at our disposal. Like batteries made from viruses we’ve discussed before, bacterial motors could be scaled up to function at the human scale, but are much more likely to be used in microscopic applications. Imagine tiny computer chips that you could could power with sewage (E. coli food), or biosensors that were powered and triggered by the bacteria around them.

The choice of E. coli bacteria gives this project a wide range for possible improvement. E. coli have whip-like tails called flagellum that allow them to propel themselves. Although they are just 3 microns long, the bacteria can travel up to 10 body lengths per second. The current linear speed of the rotor is just about 2 microns per second, so we could possibly see a ten fold increase if the bacteria speed were optimized. Likewise, only 20% of bacteria are moving the rotor in the correct direction, if this were optimized we could see a five-fold increase in force applied.

E. coli have whip like flagellum to propel themselves.

Of course, E. coli are also one of the most commonly used organisms in genetic engineering. Many of the components of MIT’s Registry of Standard Biological Parts can be spliced into E. coli, and that species is a regular at the annual iGEM competition. Although the technique hasn’t been used so far, genetic alterations to the bacteria could help make the University of Rome’s motor a viable power source for miniature devices.

There was some controversy surrounding the bacterial motor, and debate on whether or not it would work. Those familiar with physics or chemistry may know the concept of Brownian Motion. Simply stated, randomly moving particles don’t stray far from where they start. It’s generally well accepted that energy cannot be harnessed from Brownian Motion. But wait, you say, aren’t those little bacteria moving around randomly, and isn’t that motion pretty Brown? Well, the University of Rome team wrote a paper (again in ArXiv) explaining why bacteria movement, though seemingly random can still be harnessed for energy. To cut it short: energy goes into the bacteria through nutrients, so energy must be able to come out, and you can harness that energy using an asymmetric object. For an old physics student like myself, this stuff is fascinating, but I’ll let everyone else get away with a “of course it works, the rotor is turning, duh!”

While still squarely in its infancy, bacteria power is an exciting concept. Again, I doubt it will be used on the human scale because it’s not as practical as solar, wind, or even algae biofuel. On the microscopic scale though, the bacterial motors may become very important. Current battery technology is nearing it limits in miniaturization and a new paradigm is going to need to take over as our electronic devices become increasingly smaller. E. coli randomly pushing a rotor may be the new paradigm. Of course, if it isn’t widely adopted, I’m still going to think its pretty cool. I mean, hard-working bacteria powering a tiny motor – that’s a Far Side cartoon just waiting to be written. Where’s Gary Larson when you need him?

[photo credits: Roberto di Leonardo, Nicholle Rager Fuller, NSF ]

A new project from Spain has created a means of detecting water borne bacteria in seconds.

Drinking the water in a foreign country always seems like something of a gamble. Could be clean, could be a one way trip to spending the entirety of your vacation in the bathroom. Luckily, a research team at Rovira i Virgili University in Tarragona, Spain has developed a biosensor that can detect bacteria at levels as low as 1 cell per 5 mL of water. As reported in FECYT and SINC, the project utilized carbon nanotubes and fragments of DNA to detect Salmonella tyhpi, the bacteria that causes Typhoid Fever. And the best part? Water can be tested in just a few seconds.

Bacterial infections may be an inconvenience to tourists, but they are down right deadly to third world citizens. Water borne pathogens account for millions of deaths each year world wide. Typhoid Fever alone claims 500,000+ each year according to the WHO. A quick test for pathogens will greatly increase the safety of potable water, and avoid the pandemics that often accompany infected wells. If the technology can be adapted to other bacteria…we may be talking about millions of lives saved each year.

The biosensor works like a microscopic bacteria trip wire. Detection of bacteria hinges on the use of aptamers, fragments of DNA or RNA that bond to particular molecules. The Spanish team was able to develop a method of securing aptamers to the inside of carbon nanotubes. After being in the presence of Salmonella bacteria for a few seconds, those aptamers latch on to the cells. This shift generates a mild electric signal that can be detected almost instantly. Bacteria beware!

It’s remarkable that the Salmonella biosensor can find a single bacterium in 5mL of water. That’s like finding a lost dog in Central Park. Even more impressive, the count of bacteria can be determined quantitatively up to 1000 per mL. So you not only know if there’s a pathogen in your water, you can track the relative levels of the pathogens. This will help doctors and epidemiologist describe and predict the spread of disease.

The next big step for the Spanish biosensor is to find or adapt more aptamers so that other pathogens can be detected in the same manner. That may seem like a tall order, but remember that biosensors based on nanotechnology aren’t exactly new – we’ve even seen them for lung cancer breathalysers. The proverbial ‘lab-on-a-chip’ is getting closer to reality every day. Making microscopic objects as quickly and easily detected as pH will revolution medicine. And it should help you avoid losing precious beach time to Montezuma’s revenge.