Building Rhea's Factory: How AI-Designed Enzymes Could Finally Solve Plastic Recycling

Guests

• Arzu Sandıkçı, Co-founder & CEO, Rhea's Factory
• Mert Topcu, Co-founder, Rhea's Factory

In this episode:

• Why only 10% of plastic gets recycled—and why mechanical and chemical methods hit a ceiling
• How enzymatic recycling breaks plastic all the way back to its original monomers, unlike traditional methods that just shorten polymer chains
• Why enzymes are selective: they can target specific plastic types even in mixed waste streams
• The discovery of a plastic-eating bacteria in Japan that opened the door to enzymatic recycling
• How AlphaFold and the Nobel Prize in Chemistry transformed what's possible in enzyme engineering
• How Rhea's Factory uses protein language models (PLMs) and multi-step AI pipelines to design novel enzymes computationally
• The evolution from a human-orchestrated pipeline to an agentic AI scientist
• How guardrails at each pipeline step keep the AI pointed in the right direction without limiting exploration
• Why wet lab data—even just hundreds of proprietary data points—can be enough to train a powerful domain-specific prediction model
• Why Mert sometimes wants the model to hallucinate (and how high temperature settings help explore the full enzyme design space)
• The business constraint: enzymatic recycling must compete economically with cheap, oil-based plastic production
• What's next: a process agent, a 5,000-ton demo plant in California, and enzymes for new plastic types

Resources & Links

• Rhea's Factory — Enzymatic plastic recycling technology
• AlphaFold — DeepMind's AI system for protein structure prediction (inspiration for the Nobel Prize in Chemistry)
• Maven AI Evals Course — The course Teresa took to learn about evals (35% off with Teresa's affiliate link)

Chapters

00:00 Meet the Founders
01:50 Why Plastic Circularity
03:19 Mechanical vs True Recycling
04:52 Biology as the New Tool
07:20 Necklace and Pearls Analogy
13:22 Low Energy Reactor Process
17:33 Origin Story and PET Enzyme
22:52 Protein Folding and AlphaFold
28:32 AI Designed Enzymes
34:28 Protein Language Models Stack
37:14 Multi Step Protein Generation
39:00 Building on Foundation Models
40:50 Lab First Success Metrics
43:10 From Human to Agentic Orchestration
43:59 Problem Statements as Inputs
46:18 Guardrails at Every Stage
47:48 Prediction Models and Data Limits
50:03 Industrial Reality and Cost
52:30 Agentic Parallels and Orchestrators
57:45 Impact on Timelines and Diversity
01:03:23 When Hallucination Helps
01:04:09 Scaling Up and Process Agents
01:06:56 Enzyme Blends for Mixed Plastics
01:07:49 Why Clamshells Aren't Recyclable
01:09:34 Closing Thoughts and Thanks