Latest Research Converts Waste Wood into Valuable Chemicals for Fragrances & Pharmaceuticals
A novel enzyme can transform lignin waste into valuable chemicals through a hydrogen peroxide-based green processing method, providing a cleaner and more sustainable alternative to petroleum-based methods.
Lignin and Its Potential
Lignin is a rigid polymer that provides structural support in hardwoods and softwoods, and is one of the most abundant polymers on Earth. In agricultural and forestry production, lignin, as a byproduct, produces over 100 million tons annually, but about 98% of it is discarded.
However, these lignin can be converted into promising renewable and sustainable raw materials for chemicals currently obtained from fossil fuels. Recently, a newly discovered enzyme may enable efficient extraction of valuable molecules from this waste via eco-friendly green chemistry. These molecules can be used as components of perfume, flavorings, fuels, pharmaceuticals and other products, transforming a large amount of unused waste streams into valuable resources.
The Defects of Traditional Processes
"Strategies of utilizing lignin involve a combination of chemical and biological processes," said Stephen Bell, Associate Professor of Physical, Chemical, and Earth Sciences at the University of Adelaide. "Using high temperature, high pressure, strong acids, and toxic solvents to decompose polymers in the waste stream. Then, valuable compounds in the waste are extracted and undergo further chemical treatment at temperatures above 400℃ to 'upgrade' lignin. These processes are costly and harmful to the environment."
Dr. Fiona Whelan, cryo-electron microscopy expert at the Adelaide Microscopy Centre, added, "The traditional chemical synthesis of such chemicals relies on petroleum-based starting compounds and heavy metal catalysts, making them non-renewable and inherently toxic." Her findings were published in Nature Communications.
Biological Breakthrough
Hardwood lignin contains two key chemical components that require processing to produce useful compounds.
Researchers have previously discovered an enzyme that can be used to decompose one of the compounds, which is also present in softwood but have not yet discovered a biological decomposition process that can utilize the second, more complex hardwood compound (which accounts for approximately 50% of waste).
Dr. Whelan said, "Lignin biodegradation occurs in complex microbial communities. Fungal enzymes may break down rigid polymers, while bacteria absorb inactive smaller compounds and process them to obtain metabolic energy. Across the microbial world, we found a soil bacterium, Amycolatopsis Thermolava, which contains enzymes that can process lignin molecules cost-effectively, using hydrogen peroxide to drive reactions, greatly reducing the environmental harm of the value-added process."
The team used this new enzyme as a model to transform the activity driven by hydrogen peroxide into other enzymes to generate future green chemical methods for the production of high-value chemicals used in fragrance, flavor, and pharmaceutical industries.
"This new catalytic approach will support the development of other green 'enzyme factories' or biorefineries, converting lignin and other biological waste streams into valuable fine chemical libraries," said Dr. Whelan.
