Rice is the second most cultivated crop globally, generating 72.6 million metric tonnes of rice bran annually—most of which is discarded or used as low-value animal feed. But what if this underutilised by-product could become a resource for sustainable enzyme production? A study published in Journal of Fungi (Yélamos et al., 2025) explores how filamentous fungi can convert rice bran into industrially valuable enzyme cocktails.
Fungal Alchemy: Unlocking Enzyme Potential
Researchers at the Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC) in Spain isolated 16 fungal strains from rice bran, focusing on those from the Aspergillus, Penicillium, and Mucor genera. These fungi were screened for their ability to produce enzymes that break down plant materials—particularly cellulases and xylanases, key players in biofuel production, food processing, and textiles.
Best cellulase producers: Aspergillus niger var. phoenicis and Penicillium parvofructum demonstrated the highest ability to degrade cellulose, a major plant polysaccharide.
Top xylanase producers: A. terreus and A. niger var. phoenicis excelled at breaking down xylan, a key component of hemicellulose.
Multifunctional enzyme producers: P. parvofructum also secreted proteases, starch-degrading enzymes, and antifungal proteins, making it a candidate for broader applications.
Rice Bran: From By-Product to Biofactory
Rice bran contains 50% carbohydrates, 15% protein, and 20% fat, making it an ideal growth substrate for enzyme-producing fungi. The research team incubated fungal cultures in rice bran-based media and measured enzyme production over time. A. niger var. phoenicis stood out, generating the highest levels of cellulases and xylanases, while P. parvofructum was notable for secreting antifungal proteins.
Key Enzymes Identified:
β-glucosidase: Essential for converting cellulose into fermentable sugars for biofuels.
β-xylosidase: Breaks down xylan into simple sugars, aiding biofuel and food processing.
α-L-arabinofuranosidase: Important in juice clarification and animal feed.
β-galactosidase: Used in dairy and food industries to break down lactose.
Proteases and antifungal proteins: Potential applications in pharmaceuticals and biopesticides.
Beyond Enzymes: The Role of Antifungal Proteins
Interestingly, the researchers also discovered that two Penicillium species produced up to three different antifungal proteins (AFPs). These small, cysteine-rich proteins have the potential to be used as biopesticides or antimicrobial agents in agriculture and medicine. P. parvofructum in particular secreted class A and C AFPs, proteins known for their ability to inhibit fungal pathogens without harming human cells.
A Step Towards Sustainable Industrial Enzymes
Currently, industrial enzymes are often produced using costly chemical or bacterial processes. This study suggests a low-cost, eco-friendly alternative: leveraging fungal fermentation on agricultural waste. More research is needed to better understand and address outstanding challenges around scalability - can these fungi perform efficiently in industrial-scale fermentation? optimisation - fine-tuning growth conditions could enhance enzyme yields, and regulatory approval - the safety and efficacy of fungal-derived enzymes and AFPs must be validated for commercial use.
This research highlights the untapped potential of fungi in industrial biotechnology. By converting rice bran waste into high-value enzymes and bioactive proteins, filamentous fungi could provide a sustainable alternative to traditional enzyme production. With further development, fungal bioprocessing could transform how industries source enzymes—reducing reliance on synthetic production while valorising agricultural by-products.
Research Citation: Yélamos, A. M., Marcos, J. F., Manzanares, P., & Garrigues, S. (2025). Harnessing Filamentous Fungi for Enzyme Cocktail Production Through Rice Bran Bioprocessing. Journal of Fungi, 11(106).