Ricky smiled again, and shrugged. “Hey,” he said. “It gets the job done.” Those kettles in the next room were indeed tanks for controlled microbial growth. But Ricky wasn’t making beer—he was making microbes, and I had no doubt about the reason why. Unable to construct genuine nanoassemblers, Xymos was using bacteria to crank out their molecules. This was genetic engineering, not nanotechnology!
That was an excerpt from Michael Crichton’s Prey, a sci-fi novel, and an excellent read, published in 2002.
That particular quote was in reference to the protagonist discovering that a R&D company was using bacteria (in his case "Theta-d 5972 […] A strain of E. coli.") to grow nanoparticles, which in turn built nanobots. I am a lover of sci-fi novels, the more plausible, the better. Michael Crichton is a physicist, and his novels tend to be incredibly beleivable… Just read on!