Researchers from the University of Maine have used edible fungus to develop an impervious waterproof food-safe film that could grow on commonly used products like paper, denim, polyester felt and thin wood, revealing its potential to replace plastic coatings with sustainable, natural materials.
Proof-of-concept: Along with fibres made from wood, the fungus produced a layer that blocks water, oil and grease absorption, and this impervious film could be used as an alternative to single-use plastic wrap and paper cup coatings.
The How and What: Fungi are more than their mushroom caps; underground they form an extensive, interwoven network of feathery filaments called mycelium, and the surface of which naturally repels water.
Additionally, films made from the fluffy wood fibres used in paper-making — specifically, a microscopic form called cellulose nanofibrils — can create barriers for oxygen, oil and grease.
>The research team led by corresponding author Caitlin Howell displayed that edible fungi can be combined with the cellulose nanofibrils to literally grow water-resistant coatings on paper, textiles, and wood.
>To create the film, the researchers first blended T. versicolor mycelia with a nutrient-rich solution of cellulose nanofibrils.
>They applied thin layers of the mixture to denim, polyester felt, birch wood veneer and two types of paper, letting the fungus grow in a warm environment.
>Placing the samples in an oven for one day inactivated the fungus and allowed the coating to dry. It took at least three days of fungal growth for an effective water barrier to develop.
>And after four days, the newly grown layer didn’t add much thickness to the materials (about the same as a coat of paint), but it did change their colours, forming mottled yellow, orange or tan patterns.
>In addition, the fungal coating prevented other liquids from absorbing, including n-heptane, toluene and castor oil, suggesting that it could be a barrier to many liquids.
Scalable Process: The researchers say this work is a successful demonstration of a food-safe fungal coating and shows this technology’s potential to replace single-use plastic products.
>It is a scalable process for making biodegradable barriers that could help replace some single-use plastics and help reduce microplastic pollution.
Funding: University of Maine Sea Grant, funded by the National Oceanic and Atmospheric Administration’s National Sea Grant Program; a UMaine Flagship Fellowship; the National Science Foundation; and The Specialized Materials and Manufacturing Alliance for Resilient Technologies (SM²ART) programme between Oak Ridge National Laboratory and the University of Maine.
The study was published in Langmuir, a publication from the American Chemical Society (ACS) that highlights the science and application of systems and materials in which the interface dominates structure and function.
WHAT THEY SAID:
This is a scalable process for making biodegradable barriers that could help replace some single-use plastics and help reduce microplastic pollution. Our hope is that by providing more ways to potentially reduce our reliance on single-use plastics, we can help lessen the waste that ends up in landfills and the ocean; nature offers elegant, sustainable solutions to help us get there.
— CAITLIN HOWELL
Professor of Bioengineering / Expert in Biointerfaces & Sustainable Materials
University of Maine
