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FRIMEDBIO-Fri med.,helse,biol

Degradation of lignin by bacteria

Alternative title: Bakteriell nedbrytning av lignin

Awarded: NOK 7.2 mill.

The DeLignoBact project aims at identifying bacterial enzymes that are able to degrade lignin. Lignin is one of the main components of non-edible plant materials but is not utilized in an optimal way today. By gaining a better understanding of the enzymatic systems involved in lignin degradation in Nature, we will be able to utilize lignin as a renewable resource for aromatic compounds. Today, oil and gas are the main sources for aromatic compounds, hence, this project will potentially contribute to a greener technology for production of these compounds, which are used for producing a wide variety of compounds. Non-edible plant materials consist of lignocellulose, the most abundant renewable resource on Earth, which is made up by three main components: cellulose, hemicellulose, and lignin. Most biorefineries focus mainly on the utilization of cellulose, a process demanding a pretreatment of the wood. The pretreatment methods result in unfavorable changes in the lignin, reducing its value. Consequently, the lignin is often only used for combustion instead of as a renewable resource for aromatic compounds. Quite a lot of knowledge on how fungi degrade lignin exists, while the ability of bacteria to degrade lignin has been explored to a lesser extent. Hence, DeLignoBact will explore the enzymes involved in bacterial degradation of lignin. We will collect soil samples from different depths and use these to enrich for bacteria able to degrade lignin. By studying the bacteria present and the enzymes they utilize in the degradation process, we hope to identify the enzyme systems necessary for effective degradation. Preliminary results show that microorganisms can grow anaerobically with lignin as the only carbon source. In addition, we have identified a few enzymes which could be important in the lignin degradation process. Another goal for this project is to study the interplay between lignin degrading enzymes and other enzymes involved in degradation of the other components of lignocellulose: cellulose and hemicellulose.

Lignocellulose is the most abundant renewable resource on earth, consisting of cellulose, hemicellulose and lignin. Currently adopted biorefining processes for lignocellulosic biomass focus on production of glucose from cellulose and often involve pre-treatment processes that reduce lignin quality and increase lignin recalcitrance. The lignin-rich fractions emerging during biomass processing have low value and tend to be combusted, rather than being used as a renewable source for aromatic compounds. Development of enzyme-based technologies for better utilization of lignin as a renewable source for aromatic compounds is of great interest. This project will study lignin degradation by microbial communities in soil, with a special focus on bacteria, to unravel the enzyme systems involved during both aerobic an anaerobic growth. By taking the advantage of state-of-the-art meta-omics techniques we will get insight into how microbial communities and their enzyme systems adapt to various growth conditions with lignin as carbon source. Our approach will enable identification of novel enzymes involved in lignin degradation to an extent that cannot be achieved in classical enzyme discovery methods. The most interesting enzymes will be selected for in-depth characterization which will add knowledge to fundamental redox biology. We have an ambitious aim at designing a ligninolytic cocktail. Links between enzymes involved in lignin degradation and cellulose degradation will also be elucidated, which can be of value for industrial biorefineries aiming at optimizing processes for more efficient saccharification and utilization of the lignin fraction.

Funding scheme:

FRIMEDBIO-Fri med.,helse,biol

Funding Sources