Colin South

Most people fighting climate change point at smokestacks and tailpipes. Colin South points at a cow's stomach. Inside the rumen of every grazing animal lives a colony of microbes called methanogens, and their byproduct is methane - a greenhouse gas dozens of times more potent than carbon dioxide over the short term. South's company, ArkeaBio, is building a vaccine that trains the cow's own immune system to keep those microbes in check. The animal grazes as usual. The burps just get quieter.

That idea sounds like a parlor trick until you sit with the math. There are roughly 1.5 billion cattle on Earth, and pasture and rangeland animals - the ones too spread out for feed additives or controlled diets - make up about 80% of livestock emissions. You cannot put a scrubber on a herd wandering across Texas or Patagonia. But you can give the rancher a syringe. South likes to note that the entire global supply of the active antigen the vaccine would need could fit inside a single 20-foot shipping container. A planet-scale problem with a glovebox-scale ingredient.

He runs ArkeaBio from the former Hood Milk plant in Charlestown, Massachusetts - a building that once processed dairy now reverse-engineering the dairy cow. The symmetry is not lost on anyone who works there.

From a sheep farm to a PhD lab

South grew up on a 1,000-head sheep farm in New Zealand. That detail matters more than any line on his resume, because it means he understands the customer before he understands the science. He knows what a farmer will actually tolerate at the chute, what a vaccine has to cost to be worth the trip, and why a fancy lab result that does not survive contact with a paddock is worthless.

He left the farm for engineering. A bachelor's in chemical and process engineering from the University of Canterbury, then a move to the United States for a master's in engineering management and a PhD in bioprocess engineering, both from Dartmouth College. Along the way he did a stint in the New Zealand dairy industry, including time at Fonterra, the country's giant cooperative. The pattern of his whole career was already set: take a biological process, figure out how to run it at industrial scale, and find someone willing to pay for the output.

Three startups, one obsession

Before cattle, South spent two decades turning microbes into commercial products. He was the founding president of Mascoma Corporation, one of the early companies trying to make cellulosic ethanol - fuel from wood chips and crop waste rather than corn - using engineered organisms. He led Novogy and Lignol, ventures aimed at replacing petrochemicals with biochemical alternatives. Then he served as VP of strategy at Zymergen, the synthetic-biology company that tried to industrialize the design of new materials.

Read those together and a thread appears. Fuel, then chemicals, then materials, now climate-friendly livestock. Each time the bet is the same: biology can do something cheaper and cleaner than the incumbent chemistry, if you are stubborn enough to commercialize it. Cellulosic ethanol was famously hard. South kept choosing hard.

The bet on a vaccine

ArkeaBio was founded in 2021, and South took the CEO chair in January 2022. The competition in livestock methane runs toward feed additives - powders mixed into a cow's diet that suppress methane while the animal is eating them. They work, but they need to be fed continuously, which is a non-starter for animals that graze freely. South's argument is that a vaccine is the only intervention with both reach and staying power: a shot or two a year, the same way ranchers already vaccinate against other diseases, with antibodies that keep working between doses.

The science is genuinely unproven, and South says so plainly. The vaccine prompts the animal to produce antibodies that travel in saliva into the digestive tract and bind to methanogens. Early results have shown methane reductions in the 10-15% range lasting a couple of months - real, but short of the company's own bar for a minimum viable product, which it pegs at a 15-20% reduction lasting three to six months. ArkeaBio has been running cattle trials with researchers at Texas A&M University and expects the road to USDA approval to take years, not months.

What keeps the story credible is South's refusal to oversell it. In interviews he is careful to separate what the company has shown from what it still hopes to show. "We've moved a long way over the last 18 months or so," he told one trade publication. "We're confident from what we're seeing that the mechanism of action does work." That is the sentence of an engineer, not a hype man.

Handing over the wheel

In September 2025 ArkeaBio did something founders rarely do gracefully. It brought in a new CEO - Frank Wooten, co-founder of the virtual-fencing company Vence, which Merck Animal Health acquired in 2022 - and South stepped into the role of Chief Business Officer. The same week, the company closed a $7 million Series A1 co-led by Breakthrough Energy Ventures and AgriZeroNZ, pushing total funding past $40 million and setting up expanded field trials for 2026-2027.

The move reads as discipline rather than demotion. South built the company and proved the mechanism; the next phase is commercial scale and global agribusiness deals - exactly the chess he played at Mascoma and Zymergen. Putting himself where he is most useful, and letting an operator run the company, is the kind of decision that gets a founder remembered well. He was also named an Unreasonable Fellow in 2025, joining a network of entrepreneurs working on outsized problems.

If the vaccine works at scale, it becomes a piece of climate infrastructure as quiet and routine as any other shot in a vet's bag - invisible to everyone except the atmosphere. That is the prize South has been circling his whole career: the unglamorous, enormous fix. A farm kid who decided the cow was not the enemy, just an engineering problem nobody had bothered to solve.