Sauerkraut is Sandor Katz’s gateway drug. Simple and safe to make, it leads novice picklers to more offbeat practices. Illustration by Barry Blitt

The house at 40 Congress Street wouldn’t have been my first choice for lunch. It sat on a weedy lot in a dishevelled section of Asheville, North Carolina. Abandoned by its previous owners, condemned by the city, and minimally rehabilitated, it was occupied—perhaps infested is a better word—by a loose affiliation of opportunivores. The walls and ceilings, chicken coop and solar oven were held together with scrap lumber and drywall. The sinks, disconnected from the sewer, spilled their effluent into plastic buckets, providing water for root crops in the gardens. The whole compound was painted a sickly greenish gray—the unhappy marriage of twenty-three cans of surplus paint from Home Depot. “We didn’t put in the pinks,” Clover told me.

Clover’s pseudonym both signalled his emancipation from a wasteful society and offered a thin buffer against its authorities. “It came out of the security culture of the old Earth First! days,” another opportunivore told me. “If the Man comes around, you can’t give him any incriminating information.” Mostly, though, the names fit the faces: Clover was pale, slender, and sweet-natured, with fine blond hair gathered in a bun. His neighbor Catfish had droopy whiskers and fleshy cheeks. There were four men and three women in all, aged twenty to thirty-five, crammed into seven small bedrooms. Only one had a full-time job, and more than half received food stamps. They relied mostly on secondhand bicycles for transportation, and each paid two hundred dollars or less in rent. “We’re just living way simple,” Clover said. “Super low-impact, deep green.”

Along one wall of the kitchen, rows of pine and wire shelves were crowded with dumpster discoveries, most of them pristine: boxes of organic tea and artisanal pasta, garlic from Food Lion, baby spring mix from Earth Fare, tomatoes from the farmers’ market. About half the household’s food had been left somewhere to rot, Clover said, and there was often enough to share with Asheville’s other opportunivores. (A couple of months earlier, they’d unearthed a few dozen cartons of organic ice cream; before that, enough Odwalla juices to fill the bathtub.) Leftovers were pickled or composted, brewed into mead or, if they looked too dicey, fed to the chickens. “We have our standards,” a young punk with a buzz-cut scalp and a skinny ponytail told me. “We won’t dumpster McDonald’s.” But he had eaten a good deal of scavenged sushi, he said—it was all right, as long as it didn’t sit in the dumpster overnight—and his housemate had once scored a haggis. “Oh no, no,” she said, when I asked if she’d eaten it. “It was canned.”

Lunch that day was lentil soup, a bowl of which was slowly congealing on the table in front of me. The carrots and onions in it had come from a dumpster behind Amazing Savings, as had the lentils, potatoes, and most of the spices. Their color reminded me a little of the paint on the house. Next to me, Sandor Katz scooped a spoonful into his mouth and declared it excellent. A self-avowed “fermentation fetishist,” Katz travels around the country giving lectures and demonstrations, spreading the gospel of sauerkraut, dill pickles, and all foods transformed and ennobled by bacteria. His two books—“Wild Fermentation” and “The Revolution Will Not Be Microwaved”—have become manifestos and how-to manuals for a generation of underground food activists, and he’s at work on a third, definitive volume. Lunch with the opportunivores was his idea.

Katz and I were on our way to the Green Path, a gathering of herbalists, foragers, raw-milk drinkers, and roadkill eaters in the foothills of the Smoky Mountains. The groups in Katz’s network have no single agenda or ideology. Some identify themselves as punks, others as hippies, others as evangelical Christians; some live as rustically as homesteaders—the “techno-peasantry,” they call themselves; others are thoroughly plugged in. If they have a connecting thread, it’s their distrust of “dead, anonymous, industrialized, genetically engineered, and chemicalized corporate food,” as Katz has written. Americans are killing themselves with cleanliness, he believes. Every year, we waste forty per cent of the food we produce, and process, pasteurize, or irradiate much of the rest, sterilizing the live cultures that keep us healthy. Lunch from a dumpster isn’t just a form of conservation; it’s a kind of inoculation.

“This is a modern version of the ancient tradition of gleaning,” Katz said. “When the harvest is over, the community has a common-law right to pick over what’s left.” I poked at the soup with my spoon. The carrots seemed a little soft—whether overcooked or overripe, I couldn’t tell—but they tasted all right. I asked the kid with the ponytail if he’d ever brought home food that was spoiled. “Oh, hell yes!” he said, choking back a laugh. “Jesus Christ, yes!” Then he shrugged, suddenly serious. “It happens: diarrhea, food poisoning. But I think we’ve developed pretty good immune systems by now.”

To most cooks, a kitchen is a kind of battle zone—a stainless-steel arena devoted to the systematic destruction of bacteria. We fry them in oil and roast them in ovens, steam them, boil them, and sluice them with detergents. Our bodies are delicate things, easily infected, our mothers taught us, and the agents of microscopic villainy are everywhere. They lurk in raw meat, raw vegetables, and the yolks of raw eggs, on the unwashed hand and in the unmuffled sneeze, on the grimy countertop and in the undercooked pork chop.

Or maybe not. Modern hygiene has prevented countless colds, fevers, and other ailments, but its central premise is hopelessly outdated. The human body isn’t besieged; it’s saturated, infused with microbial life at every level. “There is no such thing as an individual,” Lynn Margulis, a biologist at the University of Massachusetts at Amherst, told me recently. “What we see as animals are partly just integrated sets of bacteria.” Nearly all the DNA in our bodies belongs to microorganisms: they outnumber our own cells nine to one. They process the nutrients in our guts, produce the chemicals that trigger sleep, ferment the sweat on our skin and the glucose in our muscles. (“Humans didn’t invent fermentation,” Katz likes to say. “Fermentation created us.”) They work with the immune system to mediate chemical reactions and drive out the most common infections. Even our own cells are kept alive by mitochondria—the tiny microbial engines in their cytoplasm. Bacteria are us.

“Microbes are the minimal units, the basic building blocks of life on earth,” Margulis said. About half a billion years ago, land vertebrates began to encase themselves in skin and their embryos in protective membranes, sealing off the microbes inside them and fostering ever more intimate relations with them. Humans are the acme of that evolution—walking, talking microbial vats. By now, the communities we host are so varied and interdependent that it’s hard to tell friend from enemy—the bacteria we can’t live with from those we can’t live without. E. coli, Staphylococcus aureus, and the bacteria responsible for meningitis and stomach ulcers all live peaceably inside us most of the time, turning dangerous only on rare occasions and for reasons that are poorly understood. “This cliché nonsense about good and bad bacteria, it’s so insidious,” Margulis said. “It’s this Western, dichotomized, Cartesian thing. . . . Like Jesus rising.”