Mycelial fungi in the Ascomycota and Basidiomycota groups produce keratinases that break down stubborn keratin waste like chicken feathers, hair, leather scraps, and other protein-rich leftovers. Those enzymes can turn low-value waste into animal feed, fertilizer, cosmetics, pharmaceuticals, detergents, tannery products, and bioplastics. Fungi are being positioned as small enzyme factories for one of agriculture’s messiest waste streams.