Would you wear clothes made out of muscle fibres? What if they were stronger than silk, cotton and even Kevlar, and 100% vegan?
Soon this might be possible, with a team of researchers from Washington State University teaching microbes to make muscles fibres – without harming a single animal.
The researchers, led by Cameron Sargent, repurposed a technique they previously used to engineer bacteria that could make super-strong spider silk, and taught the microbes how to make muscle fibres.
Muscle fibres are very strong, and proteins that make the muscles could potentially be used for soft robots, clothes and biocompatible sutures, but they would usually have to be harvested from animals.
“We wondered, ‘why don’t we just directly make synthetic muscles?’” says Fuzhong Zhang, senior author of the study.
“But we’re not going to harvest them from animals; we’ll use microbes to do it.
“Its production can be cheap and scalable. It may enable many applications that people had previously thought about, but with natural muscle fibres.”
The protein the microbes made is a polymer called titin, which is one of the three major protein components of muscle. It is very large, which gives it structural integrity. However, it was difficult for the microbes to produce a protein so large.
To get around this problem, the team engineering the microbes to produce and stitch together smaller segments of the protein, creating a protein that was 50 times larger than a microbe can ordinarily make.
After this, the team used a process called wet-spinning to weave the polymers into a fibre that was one-tenth the width of a human hair.
The woven fibres were stronger than Kevlar, which is used in space suits, and was able to dissipate mechanical energy as heat. The quality of the fibres, and the flexibility of the engineering of the microbes, means there may be multiple practical uses for the muscle-making microbes and synthetic biology that produces materials.
“The beauty of the system is that it’s really a platform that can be applied anywhere,” says Sargent. “We can take proteins from different natural contexts, then put them into this platform for polymerisation and create larger, longer proteins for various material applications with a greater sustainability.”
The paper was published in Nature Communications.