Turning waste from the paper industry into beneficial compounds
Oeiras, 18 October 2024
Every year, the paper industry produces millions of tons of lignin, which is treated as biowaste because it is difficult to break down and has a heterogeneous composition. However, lignin, a plant substance and one of the most abundant organic materials on Earth, can be a key source for producing high value chemicals, materials and fuel precursors. For these reasons, researchers are focusing on finding better, environmentally friendly methods to use it efficiently.
Researchers from ITQB NOVA's Microbial & Enzyme Technology laboratory have directed their efforts toward developing strategies to convert lignin-derived compounds into beneficial products, specifically by engineering bacterial proteins that accelerate chemical reactions, known as enzymes.
For most industrial process applications, the conditions are so far different from those found in nature that these enzymes need to be modified to achieve the necessary properties. In their most recent study, published in the ChemSusChem journal, the researchers successfully enhanced the performance of a specialized bacterial enzyme, laccase, to withstand harsh industrial conditions. “Besides being stable at high temperatures and tolerating high pH conditions, the engineered enzyme is 400 times more efficient at converting lignin”, explains ITQB NOVA researcher Vânia Brissos, first author of the paper.
After optimizing the enzyme, the chemical reactions were fine-tuned at ITQB NOVA’s Bioorganic Chemistry laboratory. The researchers worked to synthesize and characterize six important “natural compounds”, phenylpropanoid dimers, also known as lignans and neo-lignans. Despite being available in plants and animals, they are isolated in very low yields, usually involving lengthy protocols and large amounts of organic solvents. Furthermore, the traditional chemical synthetic methods developed pose challenges due to the toxicity of certain chemicals, the numerous time-consuming purification steps, and the large amounts of residues produced, all of which contribute to increased costs. Optimizing conditions like pH, enzyme concentration, reaction time, temperature, and oxygen levels to afford pure compounds with high yields without the need for further purification were carried out. “Our strategies are greener and faster than previous approaches, using fewer synthetic steps to obtain complex molecules in high yields, without the need for harmful solvents”, emphasizes Rita Ventura, head of this laboratory.
This collaborative effort between the two labs at ITQB NOVA marked a significant step forward in sustainable chemistry and industrial bioprocessing for the valorization of lignin and other renewable resources. “The resulting compounds have promising applications, particularly in human health, aromatics, cosmetics and polymer science”, says Lígia Martins, head of the Microbial & Enzyme Technology lab. “For instance, they have demonstrated significant health benefits as antioxidants and anti-inflammatory agents, and they may be essential in protecting against neurodegenerative diseases”, she adds. With impact in the industrial biotechnology, especially in green and medicinal chemistry and biorefinery, this work supports the full exploitation of plant biomass, a top priority in the EU and globally.
This work was supported by Fundação para a Ciência e Tecnologia (FCT), Portugal, grants 2022. 02027.PTDC, MOSTMICRO-ITQB (UIDB/04612/2020 and UIDP/04612/2020), LS4FUTURE Associated Laboratory (LA/P/0087/2020). The NMR data was acquired at CERMAX from ITQB NOVA, with equipment funded by FCT, project AAC 01/SAICT/2016.
Researchers Vânia Brissos, Márcia Rénio, Lígia Martins and Rita Ventura.
Original paper
ChemSusChem | Unlocking Lignin's Potential: Engineered Bacterial Laccases to Produce Biologically Active Molecules
Vania Brissos, Marcia Renio, Magdalena Lejmel, Ricardo Estevinho, M. Paula Robalo, M. Rita Ventura, Lígia O. Martins
