The verification of soil health could soon be as simple as asking for local bacteria. Drones or satellites could detect their responses, given in the form of different colors in response to triggers such as nutrients or contaminants.
Since they can be easily modified to produce molecules when certain conditions are met, bacteria are already largely Used as sensors. But verification of their responses generally requires a microscope and a time.
This could soon be done by taking photos with a drone and while waiting for 30 seconds, as MIT researchers have designed a system of sensors where bacteria shine in certain light wavelengths when they detect a target.
The system seems to be versatile enough to essentially detect any molecule, chemical or bacteria, good or bad. By adding two different bacteria, it could, in fact, make the fields shine in red when the pollutants stand and green when the nutrients are high.
“Thus, it can respond to metals or radiation or toxins in the soil, or the nutrients of the soil, or whatever you want it to answer,” said Christopher Voigt, biological engineer at MIT.
“Then, the release of this would be the production of this molecule which can then be detected from afar.”
The team used special cameras mounted on drones or buildings to scan soil samples patrolled by genetically modified bacteria. The samples containing the target were clearly visible, emitting a signal up to 12 times stronger than the control samples, 90 meters (295 feet).
The glow would not be visible to the naked eye – it works using hyperspectral cameras. These devices can detect hundreds of visible and infrared light wavelengths, and analyze the quantity of each present in each pixel of an image. This means that they can collect tiny color changes that would be imperceptible for other instruments, not to mention the human eye.
The team has designed bacteria to produce “reporter” molecules that can be picked up by these hyperspectral cameras. They started by performing quantum mechanical simulations of 20,170 metabolites, to find the most appropriate candidates.
“The best hyperspectral journalists (HSR) are those whose specters are the most unique and require the smallest number of enzymes to produce”, the The authors write in their article describing the work.
Finally, they settled on two promising candidates: a pigment called biliverdinwhich can give a green shade and a Bacterichlorophyllthat microbes use for photosynthesis. Enzymes to create biliverdin were designed in a soil bacteria called Pseudomonas putidaWhile an aquatic microbe called RUBRIVAX Gelatinosus won the ability to produce bacteriochlorophyll.
These outputs have been connected to the sensor circuits in bacterial genomes – in this case, to detect other bacteria that hide nearby. But in essence, the trigger can be almost anything, including chemicals in contaminated soil.
“The right thing about this technology is that you can connect and play the sensor you want”, ” said Yonatan Chemla, Environmental Microbiome engineer at MIT. “There is no reason for a sensor to be compatible with this technology.”
To test the idea, the team has placed soil or sand samples in open -open boxes, some of which contained buried discs of the target. Hyperspectral cameras on drones or roofs can take images covering hundreds or thousands of square meters, in less than 30 seconds.
And of course, the boxes containing the targets shone strongly, in contrast striking with the control samples.
Researchers disclose funding from American Department of Defense and the Ministry of Defense of Israel.
“We have been very busy in the past three years to understand what are the regulatory landscapes and what are the security problems, what are the risks, what are the advantages of this type of technology?” Chemla said.
Although the safety and regulation of these systems must still be determined, the team claims that the method is promising for continuous environmental surveillance.
“Microbial sentries have advantages as field sensors. The authors write.
“In addition, HSRs can be imagined during the day in ambient conditions and identified in spectrally complex environments, including the open ground, greenery and urban structures.”
Research was published in the journal Nature Biotechnology.