Bark is a renewable byproduct of the forest industry, but it is today poorly used and millions of tons of bark from the industry is burned every year. However, bark contains compounds with great potential for use in new sustainable materials or for their antimicrobial properties. Johan Larsbrink has received a large grant for his research on biological bark degradation. Here, he explains how this raw material could be better utilised.
Johan Larsbrink, Associate Professor at the Division of Industrial Biotechnology, has received a grant as Ascending Investigator in Biotechnology and Environmental Biotechnology from Novo Nordisk Foundation of over 15 million SEK for the upcoming five years, to investigate microbial degradation of bark and to develop tools for extracting interesting compounds from it.
Why is bark degradation interesting?
“Everyone knows what bark is, down to a small child − but we know very little about how it is degraded in nature. I find that quite surprising. Every year, several million tons of bark are produced as a side stream in forestry, but since there is a lack of strategies to process it further most of it is simply burned. It is not particularly energy efficient to burn the bark however, due to its high moisture content, but the bark also contains large amounts of so-called extractives which make it interesting. The extractives are an important part of the tree's defence against external threats such as attacks from insects and microorganisms, and can vary greatly depending on the tree species,” says Johan Larsbrink.
Microorgansisms that degrade bark monitored over time
In the project, starting in August 2024, the researchers will monitor different groups and individual species of microorganisms that can grow on bark and degrade it, to gain fundamental knowledge of the process over time. By doing this, they can identify which enzymes the microorganisms use to modify or break down the bark, and the extractives are of special interest here.
In your research group, you have previously investigated spruce bark – what is your focus in this project?
“Yes, this new project is based on pioneering work by a recent PhD graduate in the group, Amanda Ristinmaa, whose studies focused on spruce. We will now broaden the studies and look at the degradation of bark from other trees, both conifers and deciduous trees, such as birch. Hopefully, we can also include eucalyptus bark in a collaboration with the Brazilian Biorenewables National Laboratory (LNBR) in Brazil. Additionally, we will reproduce our spruce bark experiments and see if we get similar results as in our previous studies, or if the results depend for example on which batch of bark is being examined. We would like to see if there are microorganisms specialized in the degradation of bark from conifers or deciduous trees, or if there are more general bark decomposers. In the study, we can thus get an overview of the degradation of different types of trees and environments.”
Research can lead to new, sustainable products
Enzymes identified to be involved in the bark degradation, can later be used as tools to purify extractives - or to modify them to create building blocks for new materials, for example new polymers for biobased plastics or binders. Such products could replace some of the fossil-based, unsustainable products on the market.
How does the forest industry view projects that want to take advantage of the untapped potential of bark?
“We collaborate with industries that are happy to provide bark for our experiments. When the project starts in August, it is primarily on a fundamental research level, where the industry may not immediately benefit from the results, but we are part of various networks where researchers and industry meet where we can discuss what our results may lead to in the long run. Around ten percent of the bark used in the industry today is estimated to be lost due to microbial degradation during the storage process, so basic understanding of what happens in bark piles could also be valuable knowledge for reducing waste.”
What does the grant from Novo Nordisk Foundation mean to your research?
“A grant like this gives us continuity in the project and a great opportunity to reach our scientific goals. The most exciting thing is that it enables several recruitments, in this case two PhD students and one postdoc, who can work together on the same larger idea for a longer period. Of course, it also means support for continued international collaborations,” says Johan Larsbrink.
More about Johan Larsbrink’s research
Contact
- Associate Professor, Industrial Biotechnology, Life Sciences