Could microbes grow the starship? Starships grow as organisms in George Zebrowski's Macrolife, and in Octavia Butler's Lilith's Brood. A single cell could multiply into a living starship made of trillions of cells. The starship could divide and form a whole fleet of them, enough to sustain generations of human travelers. Any damage could be repaired, since every cell's DNA would contain all the blueprint of the entire structure. Our own teeth grow biofilms that survive decades of brushing and dentistry--maybe they could survive outer space.
So far, most synthetic biology looks at one molecule at a time. Synthetic biology basically extends what microbiologists call the fermentation industry. The original fermentation product was ethanol, in yeast-fermented beverages that kept water safe to drink. Today, microbes make all kinds of products, most notably antibiotics like penicillin. Pharma companies send explorers to remote parts of the globe to find exotic drug-producing strains. My students discovered a new drug producer growing from a crack in a bar counter at the local college hangout. To prove it, they first spread tester bacteria on a Petri plate; then spotted four different bar isolates on top of the testers. The isolate at left shows a clear ring where its antibiotic diffused out and killed the tester. We don't yet know what the antibiotic is, but if it's new we could patent it for Kenyon.
We imagine making products "not found in nature"--but even natural microbes make molecules that organic chemists would never dream of. Look at this antitumor agent discovered from a filamentous soil bacterium, the kind of bacteria that give soil that new smell in the springtime (Science 297:1170). Those sets of three parallel lines are each triple bonds, within a nine-carbon ring. Who would even think to draw such a thing, let alone make it? To make it, the bacteria use modular enzymes, nanoscale assembly lines that condense one functional part after another. The original nanotechnology.
In principle, microbes could produce any organic molecule. In The Highest Frontier, microbial machines "print out" any molecule or complex--even viruses, unfortunately, like flu or Ebola. A new twist on "computer virus." And in Brain Plague, where the microbes grow buildings, they develop cancers--blobs of building material that crawl off to tap a power line. Still, is it worth a try to grow a microbial starship?