AsianScientist (Aug. 17, 2020) – In a finding that could make spider silk more accessible and scalable, researchers at the RIKEN Center for Sustainable Resource Science, Japan, have succeeded in producing spider silk proteins in photosynthetic bacteria. Their results have been published in Communications Biology.
Amazingly strong and yet light, spider silk is a versatile material that is both biodegradable and biocompatible. However, getting enough silk protein is a challenge, as each tiny spider only produces a small amount.
“Spider silk has the potential to be used in the manufacture of high-performance and durable materials such as tear-resistant clothing, automobile parts and aerospace components,” explained study first author Dr. Choon Pin Foong. “Its biocompatibility makes it safe for use in biomedical applications such as drug delivery systems, implant devices and scaffolds for tissue engineering.”
Instead of breeding a large number of spiders, the team focused on the marine photosynthetic bacterium Rhodovulum sulfidophilum. This bacterium is ideal for establishing a sustainable bio-factory because it grows in seawater, requires carbon dioxide and nitrogen in the atmosphere, and uses solar energy, all of which are abundant and inexhaustible.
The researchers genetically engineered the bacterium to produce MaSp1 protein, the main component of the Nephila spider dragline which is thought to play an important role in the strength of the spider silk. Optimization of the gene sequence that they inserted into the bacterium’s genome was able to maximize the amount of silk that could be produced.
They also found that a simple recipe—artificial seawater, bicarbonate salt, nitrogen gas, yeast extract and irradiation with near-infrared light—allows R. sulfidophilum to grow well and produce the silk protein efficiently. Further observations confirmed that the surface and internal structures of the fibers produced in the bacteria were very similar to those produced naturally by spiders.
“Our current study shows the initial proof of concept for producing spider silk in photosynthetic bacteria. We are now working to mass produce spider-silk dragline proteins at higher molecular weights in our photosynthetic system,” said study corresponding author Professor Keiji Numata.
“The photosynthetic microbial cell factories, which produce bio-based and bio-degradable materials via a carbon neutral bioprocess, could help us in accomplishing some of the Sustainable Development Goals adopted by the United Nations. Our results will help provide feasible solutions for energy, water and food crises, solid waste problems and global warming.”
The article can be found at: Foong et al. (2020) A Marine Photosynthetic Microbial Cell Factory as a Platform for Spider Silk Production.
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