Secret messages through genetically engineered microbes

microorganism or microbe is an organism that is unicellular or lives in a colony of cellular organisms. The study of microorganisms is called microbiology. Microorganisms are very diverse; they include bacteria, fungi, archaea, and protists; microscopic plants (green algae); and animals such as plankton and the planarian. Some microbiologists also include viruses.

Most microorganisms are unicellular (single-celled), but this is not universal, since some multicellular organisms are microscopic, while some unicellular protists and bacteria, like Thiomargarita namibiensis, are macroscopic and visible to the naked eye.

As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle. Airborne microbes may play a role in precipitation and weather. Microbes are also exploited  in biotechnology, both in traditional food and beverage preparation, and in modern technologies based on genetic engineering. However, pathogenic microbes are harmful, since they invade and grow within other organisms, causing diseases that kill people, other animals and plants.

Secret messages through genetically engineered microbes
For years, scientists have been able to encode messages in biological molecules such as DNA or proteins. Biologist Craig Venter wrote his name, along with several quotations, into the DNA of the partially synthetic bacteria that he unveiled last year.

In the endless search to develop newer and cooler ways to send messages between people without other’s intercepting them, chemists from Tufts University working together have figured out a way to use a strain of bacteria to encode a message on a paper-like material that can then later be decoded by the receiver. Manuel Palacios and David Walta, along with their team describe in their paper published in the Proceedings of the National Academy of Sciences.

They call it: Stenography by Printed Arrays of Microbes (SPAM).

The system of coding and decoding
The system they describe uses genetically engineered strains of Escherichia coli with added fluorescent proteins. These living organisms can carry a message and release the information when conditions selected prior match the environment....

They use 7 strains containing fluorescent proteins of different wavelengths. This provides a septenary numeral system that can be translated into text.

Bacteria are printed on an agar plate and copied on a nitrocellulose membrane. The membrane is sealed and sent by post to the receiver. As long as the proteins are not expressed, the message will not be visible. The recipient stamps the membrane on agar which enables the bacteria to grow and form colonies again. When the appropriate inducer is added, the fluorescent proteins will be expressed and the colonies can be read by measuring the fluorescent reflection.

The fluorescent proteins are added to the genome of E. Coli  together with an antibiotic resistance gene. This creates a selective pressure and only bacteria that contain the resistance gene, and thus the fluorescent protein, will survive when grown on a plate with antibiotics. With no appropriate antibiotics the bacteria will lose their fluorescent properties and the message will be lost. Also the inducer, which in the experiments was IPTG, should be known by the receiver to express the fluorescent proteins. Without the proper inducers the proteins will not be expressed by E. coli as they are not essential for their growth. The team is now trying to encode messages in more robust microbes such as yeast or spore-forming bacteria; and more complex organisms, such as plants, by exploiting variation in the shapes of leaves or the patterns of roots.




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