Kraig Biocraft Laboratories Inc (KBLB)

[first mike]

The difference is not in the genes but in the producing organism.

Aren't our fibers also spider silk inspired? I believe we started with an artificial gene which would have been inspired by spider genes.

In case someone hasn't noticed silk moths are much larger than bacteria, and much more complex, as are spiders.
Spidroin-1, is the protein responsible for the great strength of spider drag line silk.
It is a Very Large Very long chain protein with a molecular weight ( a parameter that measures chain length of polymers) in the thousands.
Bacteria and yeasts simply are not large enough or complex enough to produce proteins of such high MW.
I will leave it to Jazz710 to attempt to explain the biologic production differences, but most simply put, bacteria and yeasts are simply too small and primitive to produce very long chain polymers.

KBLB's transgenic genes are closely similar in size to the original spider / spidroin-1 genes.
They contain unique synthetic coupling and promoter regions that enable them to function in the silkworm.

In contrast the genes used by the bacterial and yeast production methods are much smaller, producing much shorter, lower MW, analogs of spidroin-1, with MW in the range of 50 to 500.

The source for all of this is from papers and publication put out a few years ago by Amsilk, the first Bacterial production company.
At that time they were still hoping to make strong long fiber.
All indicators now seem to be that they have abandoned those attempts.

Someone actually did a study of the effect of gene and protein chain length on the strength of the final fiber. SURPRISE! the shorter chain molecules produced much weaker fibers!

What we have been seeing recently seems to indicate that Bolt Threads has also given up and left the competition to produce strong fiber, concentrating instead on fashion and environment. (Which in my opinion is BS, The brewing process produces tons of waste for every pound of fiber.)

Mike L.