Science

MIT makes a hydrogel shell to prevent bacterial sensors from escaping into the wild

Scientists have been developing engineered strains of bacteria that they aim to use as sensors to detect environmental pollutants. Bacteria can be used to detect pollutants such as heavy metals. If deployed to the environment, the sensors could help scientists track how pollutant levels change over time across a wide geographic area. The caveat is that there has been some concern that the GM bacteria might escape into the wild to share their genes with other organisms.

Massachusetts Institute of Technology Engineers They think they’ve devised a way to make the deployment of bacterial sensors safer by coating them with a tough hydrogel shell that prevents them from escaping into the environment. Researchers on the projects found that they could include E.

Hydrogel pellets also protect the sensors from environmental damage. The bacteria in question are designed to express the genetic circuits they usually do not possess, giving them the ability to detect different molecules. The circuits are designed so that target detection produces a green fluorescent protein or bioluminescence. The bacteria also recorded the memory of the event in the cell’s DNA.

The genetic circuits required to do this in bacteria often include antibiotic resistance genes. Researchers say that a specific gene allows them to ensure the genetic circuit is properly inserted into bacterial cells. It is easy to understand how a genetically modified bacterium that makes it resistant to antibiotics that could be harmful if released into the environment. Many bacteria can exchange genes between different species using a process called horizontal gene transfer.

To prevent this type of gene exchange, researchers in the past have used a strategy known as “chemical containment” that involves designing bacterial sensors to require an artificial molecule that they cannot access in the wild. Another challenge is that in a very large number of bacteria, there is a chance that a small number will acquire mutations that allow them to survive without the molecule.

In this study, researchers relied on physical containment by encapsulating bacteria inside the device, preventing them from escaping. In the past, materials like plastic and glass were used but they did not work because they form proliferation barriers that prevent bacteria from interacting with the molecules that need to be detected. By encapsulating bacteria in hydrogels with pores large enough to allow molecules like sugar and heavy metals inside, the bacteria are protected and still can detect heavy metal particles.

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