Strong as steel and tougher than Kevlar, spider silk is one of nature’s most impressive materials, but try as we might, we just haven’t been able to harness it for our own use on a practical scale. Most synthetic versionsaren’t completely up to scratch, but researchers from Washington University in St. Louis have now engineered bacteria to produce biosynthetic spider silk that they say performs as well as the real stuff.
Farming spiders might seem like the obvious way to get spider silk, but the arachnids just aren’t productive enough to make that viable. Synthetic versions have been spun in the past by splicing silk-producing genes from spiders into worms, goats and bacteria, but these have had issues matching nature’s wonder material.
For the new study, the researchers have gone down the bacteria route, but on the way they’ve tried to make the silk stronger on a molecular level. The key, the team says, is in the proteins that fuse together to form the strands. This process is driven by a particular repeating sequence of DNA, and the more times that sequence repeats, the bigger the protein and the stronger the resulting silk turns out.
Sounds like a simple recipe, but the first hurdle the team had to overcome was the fact that the bacteria can’t handle sequences that get too big and chop them into smaller pieces. To deal with that, the researchers added a new short sequence to the silk DNA. This triggers a chemical reaction between proteins, allowing them to fuse together to create a larger protein.
The silk protein chains created by the team measure 556 kiloDaltons (kDa, an atomic unit of measurement). That’s longer than natural silk proteins that usually measure 370 kDa, and almost twice as long as other biosynthetic spider silk proteins that max out around 285 kDa.
Bacteria build stronger biosynthetic spider silk, protein by protein [New Atlas]