As for the host that produces fibroin, it is most cost effective to use microorganisms. Still, it has been impossible to achieve a high enough production efficiency. Even with the microorganism that offers the highest production efficiency, it costs hundred millions or billions of yen to ensure an enough amount of the microorganism for a large-scale experiment.
To improve production efficiency, Spiber made improvements to the sequences of spider silk's molecules and genes. The company designed new genes, actually synthesized them and repeated fermentative production tests using microorganisms. Based on the data obtained from the tests, it tested hypotheses and kept giving feedback to the next-generation molecular design to increase productivity.
The latest gene developed by Spiber is the sixth-generation gene. Thus far, the company has synthesized more than 300 kinds of genes. Also, by optimizing the alteration of strains and culturing conditions, it improved production efficiency by 2,500 times, compared with the efficiency at the beginning of the research, solving the problem of production cost.
There has been a grave problem in the fiber spinning process. Fibroin is a protein that can hardly be melted. To melt it and spin it into fiber, a fluorine solvent such as HFIP (hexafluoroisopropanol) and HFA (hexafluoroacetone) is conventionally used. But they are extremely toxic to humans and the environments.
With this method, up to several grams of fiber can be produced. But, in consideration of the negative effects on humans and the environments and the problem of disposal of waste, it is not realistic to produce tens or hundreds of grams of fiber.
To solve this problem, Spiber developed a new technology to dissolve fibroin with a solvent that is used in large quantities for industrial purposes and stably spin it into fiber.
For those new technologies and their peripheral technologies, the company applied for 16 patents (12 in Japan and four PCT (patent cooperation treaty) patents).