BBC Science Focus

SYNTHETIC SILK

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Spider silk produced from marine bacterium

A marine bacterium has been geneticall­y engineered to produce spider silk, which has many applicatio­ns in the medical, aerospace and clothing industries.

The silk that spiders use to form the spokes of their web is called dragline silk, and it’s tough, lightweigh­t and biodegrada­ble. It’s also biocompati­ble, which means it works well with living tissue and is not attacked by an animal’s immune system, making it a sought-after material. It can be used for applicatio­ns such as durable materials, drug-delivery systems, implant devices, and scaffolds for tissue engineerin­g.

One spider can only produce trace amounts of spider silk, and because the arachnids are territoria­l and often cannibalis­tic, it’s not possible to breed large groups for this purpose. Teams around the world have therefore tried to find a Yay to generate large quantities of spider silk in the lab.

So far, researcher­s have successful­ly used plants, animal cell cultures, yeasts, and other insects to produce a silk similar to that found in nature. However, these methods are expensive to manufactur­e on a large scale.

Scientists at Japan’s RIKEN Center for Sustainabl­e Resource Science concentrat­ed their research on the purple-coloured bacterium Rhodovulum sulfidophi­lum, which is photosynth­etic. It only needs seawater, a source of sunlight, carbon dioxide and nitrogen to survive. As these are all abundant, the bacterium is perfect for producing a ‘bio-factory’.

In the study, R. sulfidophi­lum was geneticall­y modified to produce a small amount of the protein chain that makes up dragline silk. By tweaking the conditions the R. sulfidophi­lum was kept in, the researcher­s could encourage it to grow well and produce silk efficientl­y According to Keiji Numata, who led the research, the process is carbon-neutral, making it eco-friendly and sustainabl­e.

“We are now working to mass produce spider-silk dragline proteins at higher molecular weights in our photosynth­etic system,” said Numata.

“Spider silk can be used for durable materials, drugdelive­ry systems and implants”

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 ??  ?? Whether you love or hate spiders, their silk has fascinatin­g properties
Whether you love or hate spiders, their silk has fascinatin­g properties

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