Cauldron Ferm transforms microbes into continuous production systems

Cauldron Ferm has an unusual origin compared to most startups. Its foundational technology dates back several decades, possibly to the 1960s or 1970s, though the exact timeline remains somewhat unclear. What is known is that David and Polly McLennan envisioned a way to help feed the global population using protein produced from microbes.

To achieve this, they recognised the need to improve existing fermentation processes, which were both expensive and time-consuming. Traditional fermentation typically operates in batches, similar to how breweries or vineyards function. Raw materials are introduced, microbes process them for a period, and then production halts to extract the final product. While this approach works well for high-value products like alcohol, it is less viable for food production, where cost efficiency is critical.

Despite these limitations, the McLennans continued refining their approach over four decades, developing a system based on continuous fermentation. This method allows microbes to function like ongoing production lines, generating output without interruption.

“We didn’t know what we had,” said Michele Stansfield, co-founder and CEO of Cauldron Ferm. Stansfield joined the McLennans’ company in 2012 and later realised the broader potential of their work.

“We didn’t understand the challenge of continuous fermentation for synthetic biology,” she explained. Once she grasped its significance, she worked to transform the business from a small service-oriented operation into a scalable startup. “At that point, I raised a seed round and acquired the IP, physical, and business assets.”

The company has now raised $13.25 million in a Series A2 funding round led by Main Sequence Ventures, with participation from Horizons Ventures, NGS Super, and SOSV. This follows a previous $6.5 million raise in 2024. According to Stansfield, the new capital will be used to strengthen the company’s technological advantage and expand its capabilities.

Cauldron refers to its approach as “hyper fermentation,” a system designed to keep microbes operating at peak productivity. The technology can be implemented within existing batch fermentation facilities, requiring only limited modifications. Customers bring their own microbial strains, and Cauldron optimises conditions, such as nutrient supply, to maintain continuous production.

At present, the company is focused on producing fats and proteins, including whey protein, which Stansfield noted can be easily integrated into existing supply chains. However, Cauldron is also exploring additional applications as it broadens its scope.

“Sixty per cent of all inputs to the global economy can be produced from biology,” she said. “Food was where we started, but now we’re starting to really diversify.”