Biosynthesis of Carbon Nanotubes

The estimated tensile strength of a Carbon Nanotube is about 200 Giga Pascals, an order of magnitude higher than that of any other material. This makes CNT's the most likely candidate for the tether of a Space Elevator. But how to produce a nanotube, or bundle of nanotubes, that is thousands of Km's long? It seems to me that spinning nanotubes out of a furnace is a bit random. What we need is a pure, single molecule, multi-walled nanotube, no? For that we need some kind of controlled nanoassembly technique. So would biosynthesis work? Is it possible to use biological enzymes to synthesise carbon nanotubes?

Free hydrocarbons containing benzene rings tend to be extremely toxic. There are a few organisms which can degrade benzene but nothing that can synthesise it. But maybe we can genetically engineer an enyzyme which can synthesize benzine outside of living cells? Is this possible? Has anyone tried it or thought about trying it?

The only reference I could find on the net for the biosynthesis of carbon nanotubes was this sci.nanotech usenet discussion (Enzyme Manufacture of Carbon Nanotubes) between Bob Bruner (teacher at Berkeley, U.S.) and Gordon Pusch (Computational Scientist at Argonne National Laboratory).