Scientists Improve Bacteria to Eat Plastic Faster

Researchers at NUS have found a way to make bacteria work better and faster for industry.

Bacteria can be changed to make medicine, break down plastic, or capture carbon. This is done by changing the bacteria's genes many times until they work as needed. It's a slow process, especially when many genes need to be changed at the same time.

The usual method is called directed evolution, which speeds up how bacteria change in the lab. However, this method can only change a small part of the bacteria's DNA, which limits its use for industrial applications.

This method also has a problem where bacteria can change in ways that aren't related to what researchers want, making it hard to know what changes are actually helpful.

A new method developed by NUS researchers uses a virus to change bacteria and then move those changes to new bacteria. This method is called Lytic Selection and Evolution, or LySE.

LySE uses a virus that infects bacteria and then bursts them open to change a group of genes and move those changes to new bacteria. This step helps get rid of unwanted changes in the bacteria.

The system is controlled by an engineered version of the virus's DNA-copying enzyme, which is designed to make mistakes. This enzyme makes changes much faster than the bacteria's normal machinery and mostly only changes the targeted genes.

The high error rate of the enzyme also weakens the virus, preventing it from spreading too much. Researchers can control when the changes happen by adjusting the amount of virus and bacteria.

Traditionally, scientists had to choose between slow and controlled methods or fast but uncontrolled methods. The goal was to create a system that is both fast and controlled.

The team tested LySE by changing a group of genes that let bacteria eat a part of PET plastic. After a few rounds of changes, the bacteria grew 50.9% better on this plastic than before.

In a comparison test using a standard method, the bacteria grew better but didn't change in the targeted genes. Instead, they changed in other parts of their DNA, showing the problem that LySE solves.

LySE can handle larger groups of genes than current methods and will be used to create new biological systems, including enzymes designed by AI to capture carbon dioxide.

Future studies will look at how stable these changes are over long periods and if LySE works with other types of bacteria.

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Source: NUS

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